Optical film having excellent pressure resistance and display device including the same

Abstract

One embodiment of the present invention provides an optical film and a display device comprising the same, the optical film comprising: a light-transmitting substrate; and a filler dispersed in the light transmissive matrix, in which the optical film has a compressive strength of 1 mm of 10.7 N or more based on a thickness of 50 [mu] m.

Description

Technical Field

[0001] The present disclosure relates to an optical film and a display device including the optical film, and more particularly, to an optical film having excellent dent resistance. Background Art

[0002] Recently, it has been considered to use an optical film instead of glass as a cover window of a display device for the purpose of reducing the thickness and weight of the display device and increasing flexibility. In order for the optical film to be used as a cover window of a display device, the optical film needs to have excellent optical properties and excellent mechanical properties. For example, the optical film needs to have properties such as excellent strength, hardness, abrasion resistance, and flexibility.

[0003] Fillers may be added to impart the required physical properties to the optical film that requires various physical properties. The fillers may vary depending on the physical properties required for the optical film. Summary of the Invention

[0004] Technical Problem

[0005] Therefore, in view of the above problems, the present disclosure is made. One aspect of the present disclosure provides an optical film including fibrous fillers dispersed in a light-transmitting matrix.

[0006] Another aspect of the present disclosure is to provide an optical film including fibrous fillers dispersed in a light-transmitting matrix, and thus having excellent indentation hardness.

[0007] Another aspect of the present disclosure is to provide an optical film including fibrous fillers dispersed in a light-transmitting matrix, and thus having excellent dent strength.

[0008] Another aspect of the present disclosure is to provide a display device including the optical film.

[0009] Technical Solution

[0010] According to one aspect of the present disclosure, there is provided an optical film including a light-transmitting matrix and fillers dispersed in the light-transmitting matrix. Based on a thickness of 50 μm, the optical film has a 1-mm dent strength of more than 10.7 N.

[0011] The 1-mm dent strength may refer to the force with which the optical film resists compression of a probe equipped in a universal testing machine from a point where a 1-N force is applied to a depth of 1 mm in the vertical direction at a rate of 5 mm / min.

[0012] In one embodiment, the fillers may have a rod or fibrous shape.

[0013] In one embodiment, the fillers may have a length of 1 μm to 10 μm.

[0014] In one embodiment, the filler may have a diameter of 3 nm to 330 nm.

[0015] In one embodiment, the filler may have an aspect ratio of 30 to 1,000.

[0016] The aspect ratio may refer to the ratio of the length of the filler to the diameter of the filler.

[0017] In one embodiment, the filler may include at least one of glass fiber, aluminum-based fiber, titanium fiber, or fluoride fiber.

[0018] In one embodiment, the filler may contain aluminum hydroxide.

[0019] In one embodiment, based on the total weight of the optical film, the content of the filler may be 3 wt% to 50 wt%.

[0020] In one embodiment, the optical film may have a true density of 1.55 g / cm 3 to 1.67 g / cm 3 of the true density.

[0021] In one embodiment, based on a thickness of 50 μm, the optical film may have an HM of 220 MPa or more.

[0022] HM may represent the Martens hardness of the optical film, and HM may be measured using an HM-2000 at a force of 12 mN, with a running time of 12 s and a holding time of 5 s.

[0023] In one embodiment, the optical film may have an HV of 46 MPa or more.

[0024] HV may represent the Vickers hardness of the optical film, and HV may be measured using an HM-2000 at a force of 12 mN, with a running time of 12 s and a holding time of 5 s.

[0025] In one embodiment, the optical film may have a recovery rate (nIT) of 60% to 100%.

[0026] The recovery rate may be measured using a nanoindenter under the conditions of 12 mN / 12 s / creep 5 s / 24 °C, 40 RH%.

[0027] In one embodiment, the light-transmitting matrix may include at least one of imide repeating units or amide repeating units.

[0028] In one embodiment, the light-transmitting matrix may be prepared from a polymerizable composition containing at least one of diamine monomers and dianhydride compounds or dicarbonyl compounds.

[0029] The diamine monomers may include at least one of 2,2′-bis(trifluoromethyl)benzidine (TFDB), 4,4′-oxydianiline (ODA), p-phenylenediamine (pPDA), m-phenylenediamine (mPDA), p-methylenediamine (pMDA), m-methylenediamine (mMDA), 1,3-bis(3-aminophenoxy)benzene (133APB), 1,3-bis(4-aminophenoxy)benzene (134APB), 2,2′-bis[4(4-aminophenoxy)phenyl]hexafluoropropane (4BDAF), 2,2′-bis(3-aminophenyl)hexafluoropropane (33-6F), 2,2'-bis(4-aminophenyl)hexafluoropropane (44-6F), bis(4-aminophenyl)sulfone (4DDS), bis(3-aminophenyl)sulfone (3DDS), 1,3-cyclohexanediamine (13CHD), 1,4-cyclohexanediamine (14CHD), 2,2-bis(4-(4-aminophenoxy)phenyl)propane (6HMDA), 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (DBOH), or 4,4'-bis(3-aminophenoxy)diphenyl sulfone (DBSDA).

[0030] The dianhydride compounds may include at least one of 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), pyromellitic dianhydride (1,2,4,5-benzenetetracarboxylic dianhydride, PMDA), 3,3,4,4-benzophenonetetracarboxylic dianhydride (BTDA), 4,4-oxydiphthalic anhydride (ODPA), bis(3,4-dicarboxyphenyl)dimethyl-silane dianhydride (SiDA), 4,4-bis(3,4-dicarboxyphenoxy)diphenyl sulfide dianhydride (BDSDA), sulfonyldiphthalic anhydride (SO2DPA), cyclobutane-1,2,3,4-tetracarboxylic dianhydride (CBDA), or 4,4'-(4,4′-isopropylidenediphenoxy)bis(phthalic anhydride) (6HBDA).

[0031] The dicarbonyl compounds may include at least one of terephthaloyl chloride (TPC), phthaloyl chloride, isophthaloyl chloride (IPC), diphthaloyl chloride (DPDOC), 4,4'-oxybis(benzoyl chloride) (OBBOC), naphthalene-2,3-dicarbonyl chloride, or 1,4-cyclohexanedicarbonyl chloride (CHDOC).

[0032] In one embodiment, the molar ratio of the dianhydride compound to the dicarbonyl compound may be from 5:95 to 40:60.

[0033] According to another aspect of the present disclosure, a display device is provided, which includes a display panel and an optical film disposed on the display panel.

[0034] Advantageous Effects

[0035] According to an embodiment of the present disclosure, the filler included in the optical film has a rod or fiber shape and can bond to the polymer chains constituting the light-transmitting matrix. Therefore, the mechanical strength of the optical film can be improved.

[0036] When the optical film according to an embodiment of the present disclosure is used in a display device, for example, when an external force is applied to the display device using a stylus or the like, deformation can be prevented or suppressed, and the deformation resistance can be improved. In addition, when a continuous external force is applied under the same conditions, the degree of deformation can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is a schematic diagram showing an optical film according to an embodiment of the present disclosure.

[0038] Figure 2 is a cross-sectional view showing a part of a display device according to another embodiment of the present disclosure.

[0039] Figure 3 is a view showing Figure 2 an enlarged cross-sectional view of a part “P” in DETAILED DESCRIPTION

[0040] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. However, the following embodiments are provided illustratively only for a clear understanding of the present disclosure and do not limit the scope of the present disclosure.

[0041] The shapes, sizes, ratios, angles, and numbers disclosed in the drawings used to describe the embodiments of the present disclosure are merely examples, and the present disclosure is not limited to the details shown. Throughout the specification, the same reference numerals refer to the same elements. In the following description, when it is determined that the detailed description of related known functions or configurations unnecessarily obscures the gist of the present disclosure, the detailed description will be omitted.

[0042] When terms such as “include”, “have”, or “contain” are used in this specification, there may also be another part, unless “only” is also used. Unless otherwise specified, terms in the singular form may include plural meanings. In addition, when interpreting an element, even if there is no explicit description, the element will be interpreted as including an error range.

[0043] When describing positional relationships, for example, when using “above”, “over”, “below”, or “next to” to describe positional relationships, unless “adjacent” or “direct” is used, the case where there is no contact therebetween may also be included.

[0044] Spatial relative terms such as "below", "beneath", "lower", "above", and "upper" may be used in this specification to describe the relationship between a device or element and another device or element, as shown in the accompanying drawings. It should be understood that, in addition to the orientation depicted in the figures, spatial relative terms are also intended to encompass different orientations of the device during the use or operation of the device. For example, if the device in one of the drawings is inverted, an element described as "below" or "beneath" another element will be positioned "above" the other element. Thus, the exemplary terms "below" or "beneath" can encompass both the meanings of "below" and "above". In the same manner, the exemplary terms "above" or "upper" can encompass both the meanings of "above" and "below".

[0045] When describing temporal relationships, for example, when using "after", "subsequent", "next", or "before" to describe a time sequence, unless "immediately" or "directly" is used, cases of non - consecutive relationships may also be included.

[0046] It should be understood that although terms such as "first", "second", etc. may be used in this specification to describe various elements, these elements are not limited by these terms. These terms are only used to distinguish one element from another. Thus, within the technical concept of the present disclosure, a first element may be referred to as a second element.

[0047] It should be understood that the term "at least one" includes all combinations related to one or more items. For example, "at least one of the first element, the second element, and the third element" may include two or more elements selected from the first element, the second element, and the third element, as well as all combinations of each of the first element, the second element, and the third element.

[0048] The features of various embodiments of the present disclosure may be partially or completely integrated or combined with each other, and may interoperate with each other differently and be technically driven. The embodiments of the present disclosure may be implemented independently of each other, or may be implemented together in an interrelated manner.

[0049] Figure 1 A schematic diagram showing an optical film 100 according to an embodiment of the present disclosure.

[0050] According to an embodiment of the present disclosure, a film having a light transmittance is referred to as an "optical film 100".

[0051] The optical film 100 according to an embodiment of the present disclosure includes a light - transmissive matrix 110 and fillers 120 dispersed in the light - transmissive matrix 110.

[0052] The light-transmissive substrate 110 can be light-transmissive. According to an embodiment of the present disclosure, the light-transmissive substrate 110 can be flexible. For example, the optical film 100 according to an embodiment of the present disclosure can be bendable, foldable, or rollable. Thus, the optical film 100 according to an embodiment of the present disclosure can be light-transmissive and can be bendable, foldable, or rollable.

[0053] According to an embodiment of the present disclosure, the light-transmissive substrate 110 can include at least one of imide repeating units or amide repeating units.

[0054] The light-transmissive substrate 110 according to an embodiment of the present disclosure can be prepared from a composition containing a dianhydride compound and a diamine monomer. Specifically, the light-transmissive substrate 110 can contain imide repeating units formed from the dianhydride compound and the diamine monomer.

[0055] However, the light-transmissive substrate 110 according to an embodiment of the present disclosure is not limited thereto, and the light-transmissive substrate 110 can be prepared from a composition containing a dicarbonyl compound and a diamine monomer. Specifically, the light-transmissive substrate 110 can contain amide repeating units formed from the dicarbonyl compound and the diamine monomer.

[0056] In addition, the light-transmissive substrate 110 according to an embodiment of the present disclosure can be prepared from a composition that further contains a dicarbonyl compound in addition to the dianhydride compound and the diamine monomer. The light-transmissive substrate 110 according to an embodiment of the present disclosure can have imide repeating units and amide repeating units. For example, the light-transmissive substrate 110 having imide repeating units and amide repeating units can be a polyamide-imide resin.

[0057] According to an embodiment of the present disclosure, the light-transmissive substrate 110 can include polyimide-based polymers. Examples of the polyimide-based polymers can include polyimide polymers, polyamide-imide polymers, and the like. The light-transmissive substrate 110 according to an embodiment of the present disclosure can be prepared from, for example, a polyimide-based polymer resin.

[0058] According to an embodiment of the present disclosure, the light-transmissive substrate 110 can be formed from a polymerizable composition containing a diamine monomer and at least one of a dianhydride compound or a dicarbonyl compound.

[0059] The polymerizable composition according to an embodiment of the present disclosure can contain a diamine monomer.

[0060] According to an embodiment of the present disclosure, for example, the diamine monomer may include at least one of 2,2'-bis(trifluoromethyl)benzidine (TFDB), 4,4'-oxydianiline (ODA), p-phenylenediamine (pPDA), m-phenylenediamine (mPDA), p-methylenediamine (pMDA), m-methylenediamine (mMDA), 1,3-bis(3-aminophenoxy)benzene (133APB), 1,3-bis(4-aminophenoxy)benzene (134APB), 2,2'-bis[4(4-aminophenoxy)phenyl]hexafluoropropane (4BDAF), 2,2'-bis(3-aminophenyl)hexafluoropropane (33-6F), 2,2'-bis(4-aminophenyl)hexafluoropropane (44-6F), bis(4-aminophenyl)sulfone (4DDS), bis(3-aminophenyl)sulfone (3DDS), 1,3-cyclohexanediamine (13CHD), 1,4-cyclohexanediamine (14CHD), 2,2-bis(4-(4-aminophenoxy)phenyl)propane (6HMDA), 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (DBOH), or 4,4'-bis(3-aminophenoxy)diphenyl sulfone (DBSDA).

[0061] More specifically, according to an embodiment of the present disclosure, for example, the diamine compound may include at least one of 2,2'-bis(trifluoromethyl)benzidine (TFDB), 2,2'-bis(3-aminophenyl)hexafluoropropane (33-6F), 2,2'-bis(4-aminophenyl)hexafluoropropane (44-6F), bis(4-aminophenyl)sulfone (4DDS), bis(3-aminophenyl)sulfone (3DDS), or 4,4'-bis(3-aminophenoxy)diphenyl sulfone (DBSDA), but an embodiment of the present disclosure is not limited thereto.

[0062] The polymerizable composition according to an embodiment of the present disclosure may contain at least one of a dianhydride compound or a dicarbonyl compound.

[0063] According to an embodiment of the present disclosure, the dianhydride compounds may include, for example: 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), pyromellitic dianhydride (1,2,4,5-benzenetetracarboxylic dianhydride, PMDA), 3,3,4,4-benzophenonetetracarboxylic dianhydride (BTDA), 4,4'-oxydiphthalic anhydride (ODPA), bis(3,4-dicarboxyphenyl)dimethyl-silane dianhydride (SiDA), 4,4-bis(3,4-dicarboxyphenoxy)diphenyl sulfide dianhydride (BDSDA), sulfonyldiphthalic anhydride (SO2DPA), cyclobutane-1,2,3,4-tetracarboxylic dianhydride (CBDA), or 4,4'-(4,4'-isopropylidenediphenoxy)bis(phthalic anhydride) (6HBDA).

[0064] More specifically, according to an embodiment of the present disclosure, the dianhydride compounds may include, for example, at least one of 3,3,4,4-biphenyltetracarboxylic dianhydride (BPDA), 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA), pyromellitic dianhydride (1,2,4,5-benzenetetracarboxylic dianhydride, PMDA), 3,3,4,4-benzophenonetetracarboxylic dianhydride (BTDA), 4,4'-oxydiphthalic anhydride (ODPA), or cyclobutane-1,2,3,4-tetracarboxylic dianhydride (CBDA), but an embodiment of the present disclosure is not limited thereto.

[0065] According to an embodiment of the present disclosure, the dicarbonyl compounds may include, for example, at least one of terephthaloyl chloride (TPC), phthaloyl chloride, isophthaloyl chloride (IPC), diphthaloyl chloride (DPDOC), 4,4'-oxybis(benzoyl chloride) (OBBOC), naphthalene-2,3-dicarbonyl chloride, or 1,4-cyclohexanedicarbonyl chloride (CHDOC).

[0066] More specifically, according to an embodiment of the present disclosure, the dicarbonyl compounds may include, for example, terephthaloyl chloride (TPC), phthaloyl chloride, or isophthaloyl chloride, but an embodiment of the present disclosure is not limited thereto.

[0067] According to an embodiment of the present disclosure, the total equivalent weight of the dianhydride compounds and the dicarbonyl compounds may be substantially the same as the equivalent weight of the diamine monomers.

[0068] To ensure excellent mechanical properties, the polymerizable composition according to an embodiment of the present disclosure may contain 60 mol% or more of the dicarbonyl compounds relative to the total moles of the dianhydride compounds and the dicarbonyl compounds.

[0069] For example, the molar ratio of the dianhydride compound and the dicarbonyl compound may be in the range of 5:95 to 40:60.

[0070] The light-transmissive substrate 110 may have a thickness sufficient to protect the display panel by the optical film 100. For example, the light-transmissive substrate 110 may have a thickness of 10 μm to 100 μm. The thickness of the light-transmissive substrate 110 may be the same as the thickness of the optical film 100.

[0071] The filler 120 may have a rod or fiber shape. Hereinafter, a shape in which the length is greater than the diameter is referred to as a "fiber shape". The fiber shape may also be referred to as a "filament shape". According to an embodiment of the present disclosure, the length of the filler 120 may be greater than twice its diameter.

[0072] According to an embodiment of the present disclosure, the filler 120 is arranged in parallel with the polymer resin included in the light-transmissive substrate 110. For example, the filler 120 may be bonded to the main chain of the polymer resin by secondary bonds such as hydrogen bonds or dipole moments and may be arranged in parallel with the main chain in the same direction as the main chain.

[0073] According to an embodiment of the present disclosure, since the filler 120 has a fiber shape, the polymer chains constituting the light-transmissive substrate 110 may be joined (or linked or connected). Therefore, the stability and arrangement characteristics of the polymer chains may be improved, the mechanical properties of the light-transmissive substrate 110 may be improved, and the mechanical properties of the optical film 100 may also be improved.

[0074] According to an embodiment of the present disclosure, the aspect ratio of the filler 120 may be in the range of 30 to 1,000. The aspect ratio refers to the ratio of the length of the filler 120 to the diameter.

[0075] When the aspect ratio of the filler 120 is less than 30, the filler 120 is not long enough and cannot sufficiently perform the function of joining the polymer chains to each other, so the function of improving the stability and arrangement characteristics of the polymer chains cannot be fully exerted.

[0076] When the aspect ratio of the filler 120 is greater than 1,000, the filler 120 may reduce the dispersibility of the filler 120 and cause the filler 120 to agglomerate in the light-transmissive substrate 110 due to the excessive length. Therefore, the optical film 100 may have a reduced light transmittance, an increased haze, and deteriorated optical properties. In addition, the mechanical strength of the optical film 100 may be reduced in the region where the filler 120 agglomerates.

[0077] According to an embodiment of the present invention, the length of the filler 120 may be in the range of 1 μm to 10 μm.

[0078] When the length of the filler 120 is less than 1 μm, the function of the filler 120 to bond polymer chains may not be fully exerted.

[0079] When the length of the filler 120 is greater than 10 μm, the dispersibility of the filler 120 may decrease. Therefore, agglomeration of the filler 120 may occur within the light-transmitting matrix 110, and gelation may easily occur due to the interaction with polymer chains. As a result, the optical film 100 may have a reduced light transmittance, an increased haze, and deteriorated optical properties.

[0080] According to one embodiment of the present disclosure, the diameter of the filler 120 may be in the range of 3 nm to 330 nm.

[0081] When the diameter of the filler 120 is less than 3 nm, the stability of the filler 120 may decrease, and the filler 120 may be cut or damaged. In addition, the filler 120 may contaminate the optical film 100 and increase the haze of the optical film 100.

[0082] When the diameter of the filler 120 is greater than 330 nm, it is difficult for the filler 120 to have a fibrous shape, and the optical film 100 may have an increased haze and a reduced transmittance.

[0083] There is no particular limitation on the type of the filler 120. Any filler can be used as the filler 120 according to one embodiment of the present disclosure without limitation as long as it has a fibrous shape. The filler 120 may be inorganic or organic. The filler 120 may include at least one of inorganic fibers, organic fibers, or organic-inorganic hybrid fibers.

[0084] More specifically, the filler 120 may have a fibrous shape. For example, the filler 120 may have a single-strand fiber shape, a multi-strand fiber shape, or a branched shape, where the multi-strands are arranged in a branched form based on a central strand.

[0085] According to one embodiment of the present disclosure, the filler 120 may include at least one of glass fibers, aluminum-based fibers, titanium fibers, or fluoride fibers.

[0086] The glass fibers may contain SiO2 and may further contain other components in addition to SiO2. The aluminum-based fibers contain aluminum oxyhydroxide (AlO(OH)). The aluminum-based fibers may further contain other components in addition to aluminum oxyhydroxide (AlO(OH)). The titanium fibers may contain TiO2. In addition to TiO2, the titanium fibers may also contain other components. The fluoride fibers may contain at least one of polytetrafluoroethylene (PTFE) or polyvinylidene fluoride (PVDF), and may further contain other components in addition to PTFE and PVDF.

[0087] According to an embodiment of the present disclosure, the filler 120 may include aluminum-based fibers. The aluminum-based fibers may include boehmite alumina.

[0088] According to an embodiment of the present disclosure, the filler 120 may include boehmite alumina. Boehmite alumina, also known as "boehmite", may be represented by γ-AlO(OH). More specifically, the boehmite alumina may include a unit structure represented by any one of the following Formula 1, Formula 2, and Formula 3.

[0089] [Formula 1]

[0090]

[0091] [Formula 2]

[0092]

[0093] [Formula 3]

[0094]

[0095] Wherein, n is in the range of 50 to 10,000, m is in the range of 50 to 10,000, and p is in the range of 100 to 20,000.

[0096] When the structures of Formula 1, Formula 2, and Formula 3 are expanded to better understand the structure of the filler 120, the filler 120 may be represented by any one of Formula 4, Formula 5, and Formula 6.

[0097] The structure represented by Formula 1 may be represented by, for example, the following Formula 4. The following Formula 4 corresponds to the structure of Formula 1, wherein n is 5.

[0098] [Formula 4]

[0099]

[0100] The structure represented by Formula 2 may be represented by, for example, the following Formula 5. The following Formula 5 corresponds to the structure of Formula 2, wherein m is 4.

[0101] [Formula 5]

[0102]

[0103] The structure represented by Formula 3 may be represented by, for example, the following Formula 6. The following Formula 6 corresponds to the structure of Formula 3, wherein p is 3.

[0104] [Formula 6]

[0105]

[0106] In Formulas 4 to 6, "*" represents the bonding position.

[0107] According to one embodiment of the present disclosure, SiO2 may have a unit structure represented by Formula 7 below.

[0108] [Formula 7]

[0109]

[0110] According to one embodiment of the present disclosure, the filler 120 may be surface-treated. For example, the filler 120 may be surface-treated with an organic compound having an alkoxy group.

[0111] According to one embodiment of the present disclosure, the filler 120 may cause appropriate light scattering to improve the optical properties of the optical film 100. To enhance the light scattering effect, the content of the filler 120 in the optical film 100 may be adjusted.

[0112] According to one embodiment of the present disclosure, based on the total weight of the optical film 100, the content of the filler 120 may be 3 wt% to 50 wt%. More specifically, based on the total weight of the optical film 100, the content of the filler 120 may be adjusted to 4 wt% to 30 wt%, or may be 5 wt% to 20 wt%.

[0113] When the content of the filler 120 is less than 3 wt% based on the total weight of the optical film 100, the light scattering effect of the filler 120 is insufficient, so the effect of improving the light transmittance of the optical film 10 cannot be obtained, and the filler 120 cannot fully perform the function of bonding polymer chains.

[0114] On the other hand, when the content of the filler 120 is higher than 50 wt% based on the total weight of the optical film 100, the dispersibility of the filler 120 may be reduced, the haze of the optical film 100 may be reduced, agglomeration of the filler 120 may occur due to the excess of the filler 120, and the agglomerated filler 120 blocks light, which may reduce the light transmittance of the optical film 100.

[0115] The true density of the optical film 100 according to one embodiment of the present disclosure may be 1.55 g / cm 3 to 1.67 g / cm 3 .

[0116] The true density refers to the density of the solid excluding the voids of the optical film 100, and when the material is small, the true density refers to the density of only the part specifically filled by the material excluding the voids between the particles. According to one embodiment of the present disclosure, the true density refers to the density of only the part filled with the light-transmitting matrix 110 and the filler 120, excluding the voids. The true density of the optical film 100 may be measured using, for example, an Accupyc II 1340 pycnometer.

[0117] When the filler 120 according to an embodiment of the present disclosure has a fibrous shape, it may have a higher true density than spherical fillers at the same weight. For example, when the fibrous filler 120 is added in an amount of 20% of the total weight, the true density of the optical film 100 is equal to that when the spherical filler 120 is added in an amount of 40% of the total weight. Therefore, the fibrous filler 120 may be advantageous not only in mechanical properties but also in optical properties.

[0118] Figure 2 is a cross-sectional view showing a part of a display device 200 according to another embodiment of the present disclosure, Figure 3 is Figure 2 an enlarged cross-sectional view of "P" in.

[0119] Referring to Figure 2 , a display device 200 according to another embodiment of the present disclosure includes a display panel 501 and an optical film 100 on the display panel 501.

[0120] Referring to Figure 2 and Figure 3 , the display panel 501 includes a substrate 510, thin film transistors TFT on the substrate 510, and an organic light emitting device 570 connected to the thin film transistors TFT. The organic light emitting device 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. Figure 2 and Figure 3 The display device 200 shown is an organic light emitting display device.

[0121] The substrate 510 may be made of glass or plastic. Specifically, the substrate 510 may be made of plastic such as polyimide resin or an optical film. Although not shown, a buffer layer may be provided on the substrate 510.

[0122] The thin film transistors TFT are provided on the substrate 510. The thin film transistors TFT include a semiconductor layer 520, a gate electrode 530 insulated from the semiconductor layer 520 and at least partially overlapping 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.

[0123] Referring to Figure 3 , a gate insulating layer 535 is provided between the gate electrode 530 and the semiconductor layer 520. An interlayer insulating layer 551 may be provided on the gate electrode 530, and the source electrode 541 and the drain electrode 542 may be provided on the interlayer insulating layer 551.

[0124] A planarization layer 552 is provided on the thin film transistors TFT to planarize the top of the thin film transistors TFT.

[0125] The first electrode 571 is disposed on the planarization layer 552. The first electrode 571 is connected to the thin film transistor TFT through a contact hole formed in the planarization layer 552.

[0126] The bank layer 580 is disposed on the planarization layer 552 in a part of the first electrode 571 to define a pixel region or a light emitting region. For example, the bank layer 580 is disposed in a matrix form at the boundaries between a plurality of pixels to define corresponding pixel regions.

[0127] 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 two or more light emitting layers stacked in the vertical direction. Light of any one of red, green, and blue colors may be emitted from the organic light emitting layer 572, and white light may be emitted therefrom.

[0128] The second electrode 573 is disposed on the organic light emitting layer 572.

[0129] The first electrode 571, the organic light emitting layer 572, and the second electrode 573 may be stacked to form an organic light emitting device 570.

[0130] Although not shown, when the organic light emitting layer 572 emits white light, each pixel may include a color filter for filtering white light emitted from the organic light emitting layer 572 based on a specific wavelength. The color filter is formed on the optical path.

[0131] The 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 layer and at least one inorganic layer, and the at least one organic layer and the at least one inorganic layer may be alternately disposed.

[0132] The optical film 100 is disposed on the display panel 501 having the above stacked structure. The optical film 100 includes a light transmissive matrix 110 and fillers 120 dispersed in the light transmissive matrix 110.

[0133] Based on a thickness of 50 μm, the optical film 100 according to an embodiment of the present disclosure may have an HM of 220 MPa or more. HM refers to the Martens hardness of the optical film 100 according to the embodiment of the present disclosure. The unit of Martens hardness is defined as MPa.

[0134] The Martens hardness of the optical film 100 according to an embodiment of the present disclosure is obtained by: measuring the surface hardness of an indentation formed by pressing the light transmissive matrix 110 with a pyramidal diamond tip; calculating HM = A / B, where the load is A kg and the surface area is B mm 2; Then convert the result to MPa. The Martens hardness can be measured under the conditions of 12 mN / running time 12 s / holding time 5 s.

[0135] The Martens hardness of the optical film 100 can be measured using a Martens hardness tester such as the HM-2000 from Fisher Scientific International, Inc.

[0136] The optical film 100 according to an embodiment of the present disclosure may have an HM of 220 MPa to 300 MPa. More specifically, the optical film 100 may have an HM of 240 MPa to 280 MPa.

[0137] When the HM of the optical film 100 is less than 220 MPa, the optical film 100 may be vulnerable to external dents. For example, when an external force is applied to the outside of the optical film 100, the optical film 100 may be easily scratched or cracked.

[0138] Based on a thickness of 50 μm, the optical film 100 according to an embodiment of the present disclosure may have an HV of 46 or more. HV represents the Vickers hardness of the optical film 100 according to the embodiment of the present disclosure.

[0139] The Vickers hardness of the optical film 100 according to the embodiment of the present disclosure is obtained by measuring the surface hardness of the indentation generated when pressing the light-transmitting substrate 110 with a pyramidal diamond tip and calculating HV = C / D, where the load is C kg and the surface area is D mm 2 . The Vickers hardness can be measured under the conditions of 12 mN / running time 12 s / holding time 5 s.

[0140] The Vickers hardness of the optical film 100 can be measured using a Vickers hardness tester such as the HM-2000 from Fisher Scientific International, Inc.

[0141] When the HV of the optical film 100 is less than 46, the optical film 100 may be vulnerable to external dents. For example, when an external force is applied to the outside of the optical film 100, the optical film 100 may be easily scratched or cracked.

[0142] Based on 50 μm, the optical film 100 according to the embodiment of the present disclosure may have a 1 mm indentation strength of 10.7 N or more. The basic unit of the 1 mm indentation strength is defined as N.

[0143] The term "1 mm indentation strength" can be defined as the force with which the optical film 100 resists compression from the point where a 1 N force is applied to a depth of 1 mm in the vertical direction.

[0144] The 1mm indentation strength is an index of the surface hardness of the optical film 100. Excellent 1mm indentation strength means high resistance to external forces.

[0145] For example, the 1mm indentation strength can be measured as follows: First, a sample of the optical film 100 according to the embodiments of the present disclosure is made into a size of 60mm x 60mm. The prepared sample of the optical film 100 is placed on a fixing device having a circular hole in the center, and then the sample of the optical film 100 is fixed with a clamp. A probe with a cylindrical head having a diameter of 1.59mm installed in a universal testing machine presses the sample of the optical film 100 in the vertical direction at a speed of 5mm / min. The force measured when pressing from the point where a force of 1N is applied to the probe as a reference point to a depth of 1mm can be measured as the 1mm indentation strength of the optical film 100. For example, a universal testing machine from Instron Corporation, a fixed support (S1-11855), a clamp, and a probe (2830-005) can be used to measure the 1mm indentation strength.

[0146] When the 1mm indentation strength of the optical film 100 is less than 10.7N, for example, when the optical film 100 is used as a cover window of the display device 200, indentations, scratches, etc. may be formed by external forces generated from a stylus, nails, foreign objects, etc. on the cover window, which may deteriorate the external quality of the cover window.

[0147] The optical film 100 according to the embodiments of the present disclosure can have a recovery rate (nIT) of 60% to 100%. The basic unit of the recovery rate is defined as a percentage (%).

[0148] The recovery rate of the optical film 100 is determined, for example, by using a nanoindentation instrument to apply a load of 12mN to the optical film 100 for 12 seconds at a temperature of 24°C and a humidity of 40RH%, pressing the optical film 100 so that the optical film 100 is stationary at the maximum pressing point for 5 seconds, and then measuring the degree to which the optical film 100 has been pressed when the applied load is removed in the reverse direction (12mN / 12s / creep 5s / 24°C, 40RH%). The nanoindentation instrument used in this specification can be, for example, model HM2000 from Fischer.

[0149] When the recovery rate of the optical film 100 is less than 60%, the optical film 100 lacks a restoring force when unfolded, resulting in the retention of folding indentations or pressing indentations, and it is difficult to be applied to foldable or rollable displays.

[0150] Hereinafter, a method for manufacturing the optical film 100 according to another embodiment of the present disclosure will be described.

[0151] A method of manufacturing an optical film 100 according to an embodiment of the present disclosure includes: preparing a polyimide resin powder; preparing a light-transmissive resin solution using the polyimide resin powder; preparing a filler dispersion; mixing the filler dispersion with the polyimide resin solution to prepare a filler resin mixture in which a filler 120 is dispersed; and preparing the optical film 100 using the prepared filler resin mixture. Hereinafter, each step will be described in detail.

[0152] According to an embodiment of the present disclosure, the polyimide resin solution can be used as a resin solution for forming a light-transmissive matrix 110.

[0153] A method of manufacturing an optical film 100 according to an embodiment of the present disclosure includes preparing a polyimide resin powder.

[0154] More specifically, according to an embodiment of the present disclosure, preparing the polyimide resin powder includes preparing a first reaction solution using a diamine monomer and a dianhydride compound, adding a dicarbonyl compound to the first reaction solution, and then reacting to prepare a second reaction solution, adding a dehydrating agent and an imidization catalyst to the second reaction solution, and then reacting to prepare a third reaction solution, and treating the third reaction solution to prepare a solid polymer resin.

[0155] To prepare the polyimide resin powder, first, a first reaction solution is prepared using a diamine monomer and a dianhydride compound.

[0156] The first solvent for preparing the first reaction solution can be, for example, a polar aprotic organic solvent such as N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), 1-methyl-2-pyrrolidone (NMP), m-cresol, tetrahydrofuran (THF), chloroform, methyl ethyl ketone (MEK), or a mixture thereof. However, the first solvent according to an embodiment of the present disclosure is not limited thereto, and other solvents can be used as the first solvent.

[0157] Specific types of the diamine monomer and the dianhydride compound have been described, and thus the description of redundant information will be omitted.

[0158] According to an embodiment of the present disclosure, the first reaction solution can contain polyamic acid and polyimide repeating units.

[0159] Then, a dicarbonyl compound is added to the first reaction solution and reacted to form a second reaction solution. For example, the dicarbonyl compound can be added to the first reaction solution 1 to 24 hours after the first reaction solution is formed. More specifically, the dicarbonyl compound can be added to the first reaction solution 1 to 20 hours after the first reaction solution is formed.

[0160] According to an embodiment of the present disclosure, when starting to add a dicarbonyl compound to the first reaction solution, the reaction solution is referred to as the "second reaction solution".

[0161] Specific types of dicarbonyl compounds have been described, and thus the description of redundant information will be omitted.

[0162] According to an embodiment of the present disclosure, the total equivalent weight of the dianhydride compound and the dicarbonyl compound can be substantially the same as the equivalent weight of the diamine monomer.

[0163] According to an embodiment of the present disclosure, the molar ratio of the dianhydride compound to the dicarbonyl compound can be in the range of 5:95 to 40:60.

[0164] Then, a dehydrating agent and an imidization catalyst are added to the second reaction solution and reacted to prepare a third reaction solution.

[0165] According to an embodiment of the present disclosure, after adding the dehydrating agent and the imidization catalyst to the second reaction solution, stirring is carried out at a temperature of 60 °C to 80 °C under reflux for 30 minutes to 2 hours. Thus, a third reaction solution can be prepared.

[0166] As the dehydrating agent, an acid anhydride such as acetic anhydride, propionic anhydride, isobutyric anhydride, pivalic anhydride, butyric anhydride or isovaleric anhydride can be used.

[0167] As the imidization catalyst, a tertiary amine such as isoquinoline, β-picoline or pyridine can be used.

[0168] Then, the third reaction solution is processed to prepare a solid polymer resin.

[0169] To prepare the solid polymer resin, a second solvent can be added to the third reaction solution. The second solvent can be, for example, ethanol, methanol, hexane, distilled water, etc. The second solvent can be used alone or as a combination of two or more types.

[0170] When a solvent that is miscible with the first solvent and has a low solubility in the polymer resin is added as the second solvent to the third reaction solution, the solid polymer resin precipitates as a powder. The precipitate can be filtered and dried to prepare a high-purity solid polymer resin. When removing the liquid component during the process of filtering the precipitate, unreacted monomers, oligomers, additives and reaction by-products can also be removed.

[0171] The polymer resin thus obtained can be in a solid powder state and can contain imide repeating units and amide repeating units. The polymer resin can be a polyimide resin, such as a polyamide-imide resin. The polymer resin is also referred to as a "polymerizable composition".

[0172] According to an embodiment of the present disclosure, a method of manufacturing the optical film 100 may include preparing a polyimide resin solution using polyimide resin powder.

[0173] To prepare the polyimide resin solution using the polyimide resin powder, the polyimide resin powder may be dissolved in a third solvent. N,N-dimethylacetamide (DMAc) may be used as the third solvent. However, an embodiment of the present disclosure is not limited thereto, and another known solvent may be used as the third solvent.

[0174] According to an embodiment of the present disclosure, a method of manufacturing the optical film 100 may include preparing a filler dispersion.

[0175] Fiber-shaped filler 120, for example, fiber-shaped filler 120 having a high aspect ratio, is longer in length compared to the diameter, and thus can be easily entangled or aggregated in the light-transmitting matrix 110. Therefore, the filler 120 requires excellent dispersibility in the filler resin mixture.

[0176] For example, the filler dispersion may be prepared by dispersing the filler 120 in a fourth solvent. The fourth solvent may include at least one of N,N-dimethylacetamide (DMAc) or methyl ethyl ketone (MEK). However, an embodiment of the present disclosure is not limited thereto, and another known solvent may be used as the fourth solvent.

[0177] According to an embodiment of the present disclosure, in order to make the filler 120 have excellent dispersibility in the filler resin mixture, the filler dispersion may be separately prepared and then mixed with the polyimide resin solution.

[0178] More specifically, based on the total weight of the filler dispersion, the filler dispersion may include, for example, 75 wt% to 85 wt% of DMAc (N,N-dimethylacetamide), 5 wt% to 10 wt% of acetic acid, 2 wt% to 7 wt% of p-toluenesulfonic acid (PTSA), and 10 wt% of the filler 120.

[0179] p-Toluenesulfonic acid (PTSA) may be used as an additive in the filler dispersion to improve the dispersibility of the filler 120. However, the embodiments of the present disclosure are not limited thereto, and other known additives may be used to improve the dispersibility of the filler 120.

[0180] Acetic acid may be used as a pH regulator in the filler dispersion to prevent the filler 120 from aggregating or agglomerating and to improve the dispersion stability. However, the embodiments of the present disclosure are not limited thereto, and another known weak acid may be used to prevent the aggregation or agglomeration of the filler 120 and to improve the dispersion stability.

[0181] According to an embodiment of the present disclosure, the content of the filler 120 in the optical film 100 can be adjusted according to the amount of the filler dispersion mixed when the polyimide resin solution is mixed with the filler dispersion.

[0182] According to an embodiment of the present disclosure, the method of manufacturing the optical film 100 may include manufacturing the optical film 100 using the prepared filler resin mixture.

[0183] According to an embodiment of the present disclosure, in order to improve the dispersibility of the filler 120 in the filler resin mixture after preparing the filler resin mixture by mixing the filler dispersion with the polyimide resin solution, for example, the pH of the filler resin mixture can be adjusted. For example, the pH of the filler resin mixture can be adjusted to the range of 4 to 7. Thus, agglomeration or aggregation of the filler 120 can be prevented.

[0184] Then, the filler resin mixture is cast, dried, and heat-treated to form the optical film 100. According to an embodiment of the present disclosure, the film formed by casting the filler resin mixture may be referred to as a "cast film", and the film produced by drying and heat-treating the cast film may be referred to as the "optical film 100". The cast film may be referred to as an "uncured film".

[0185] In addition, convection can be prevented during the drying and heat-treatment of the cast film formed by casting, so that the filler 120 can be oriented in a specific direction.

[0186] Specifically, when convection occurs inside the cast film dried using heat, the orientation of the filler 120 may be reduced. Therefore, the cast film can be dried slowly to prevent convection. For example, the drying of the cast film can be carried out while raising the temperature from 80 °C to 120 °C at a rate of 1 °C per minute. When drying is carried out to a certain level, the orientation of the filler 120 can be fixed.

[0187] The optical film 100 according to an embodiment of the present disclosure can be manufactured according to the method.

[0188] Hereinafter, the present disclosure will be described in more detail with reference to Preparation Examples and Examples. However, the following Preparation Examples and Examples should not be construed as limiting the scope of the present disclosure.

[0189] <Preparation Example: Preparation of Polymer-Imide Polymer Solid>

[0190] While purging the reactor with nitrogen, 701.979 g of N,N-dimethylacetamide (DMAc) was charged into a 1 L reactor equipped with a stirrer, a nitrogen syringe, a dropping funnel, a temperature controller, and a cooler. Then, the temperature of the reactor was adjusted to 25 °C, 54.439 g (0.17 mol) of bis(trifluoromethyl)benzidine (TFDB) was dissolved therein, and the temperature of the solution was maintained at 25 °C. 5.668 g (0.029 mol) of 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA) was added thereto, and then completely dissolved by stirring for 3 hours. Then, 12.839 g (0.029 mol) of 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) was added thereto and completely dissolved therein. After the reactor temperature was lowered to 10 °C, 22.779 g (0.112 mol) of terephthaloyl chloride (TPC) was added thereto, and the reaction was carried out at 25 °C for 12 hours to obtain a polymer solution with a solid concentration of 12% by weight.

[0191] 10.06 g of pyridine and 12.99 g of acetic anhydride were added to the obtained polymer solution, stirred for 30 minutes, heated at 80 °C, stirred at the same temperature for 1 hour to cause the reaction to occur, and then cooled to room temperature. 20 L of methanol was added to the obtained polymer solution to precipitate the solid. The precipitated solid was filtered, crushed, washed with 2 L of methanol, and dried under vacuum at 100 °C for more than 6 hours to prepare a polyimide-based polymer solid as a powder. The prepared polyimide-based polymer solid is a polyamide-imide polymer solid, which is referred to as a "polymerizable composition".

[0192] <Example 1>

[0193] While maintaining the temperature of the reactor at 10 °C, 723.46 g of DMAc (the first solvent) was added to a 1 L reactor, and the reactor was stirred for a predetermined period of time. Then, 110 g of polyamide-imide (polyimide-based resin powder) prepared as a solid powder in the preparation example was added to the reactor, stirred for 1 hour, and heated to 25 °C to prepare a polyimide-based resin solution.

[0194] In addition, a filler dispersion was prepared separately from the polyimide resin solution. A hydroxyaluminum oxide fiber dispersion was prepared as the filler dispersion.

[0195] More specifically, based on the total weight of the filler dispersion, a filler dispersion containing 80% by weight of DMAc (N,N-dimethylacetamide, the second solution), 5% by weight of acetic acid, 5% by weight of p-toluenesulfonic acid (PTSA), and 10% by weight of filler 120 was prepared. Here, the filler 120 used in this specification is hydroxyaluminum oxide fibers with an average diameter of 4 nm and an average length of 1,500 nm.

[0196] Using an air cylinder pump, 55 g of the prepared filler dispersion was slowly added to the prepared liquid polyimide resin solution over 1 hour to prepare a filler resin mixture containing the filler dispersion and the polyimide resin solution. The filler dispersion was used such that the content of filler 120 was 10% by weight based on the total weight of the solid content (polyimide resin component + filler).

[0197] The pH of the filler resin mixture was measured immediately after preparation. As a result, the pH was higher than 7. To improve the dispersion and alignment characteristics of filler 120, a weak acid such as acetic acid was added to the filler resin mixture to adjust the pH of the filler resin mixture to the range of 4 to 7, particularly pH 6.5. The thus-prepared filler resin mixture was a polyimide-based resin solution in which fibrous filler 120 was dispersed.

[0198] The obtained filler resin mixture was cast. A casting substrate was used for casting. At this time, there was no particular limitation on the type of the casting substrate. The casting substrate may be a glass substrate, a stainless steel (SUS) substrate, a Teflon substrate, etc. According to one embodiment of the present disclosure, a glass substrate was used as the casting substrate.

[0199] Specifically, the obtained filler resin mixture was applied to the glass substrate and cast. To improve the orientation of filler 120, the filler resin mixture was applied to the glass substrate (casting substrate), and then cast while applying a force of 30 N in a direction perpendicular to the glass substrate. As a result, a cast film was produced.

[0200] Specifically, the cast film was prepared by slowly drying in a hot air oven at 80°C at a rate of 1°C / 1 min for about 40 minutes to 120°C to maintain the orientation of filler 120. Then, the obtained film was peeled off from the glass substrate and fixed to a frame with pins.

[0201] The frame with the optical film fixed thereon was slowly heated from 100°C to 280°C in a vacuum oven over 2 hours, slowly cooled, and separated from the frame to obtain an optical film. The optical film was heated again at 250°C for 5 minutes.

[0202] As a result, an optical film 100 with a thickness of 50 μm and including a light-transmitting matrix 110 and filler 120 dispersed in the light-transmitting matrix 110 was completed.

[0203] <Examples 2 and 3>

[0204] An optical film 100 was prepared under the conditions of Table 1 in the same manner as in Example 1, and was respectively referred to as "Examples 2 and 3".

[0205] <Comparative Example 1>

[0206] An optical film 100 was prepared under the conditions of Table 1 in the same manner as in Example 1, except that filler 120 was not added and the pH of the first mixed solution was changed, and it was designated as "Comparative Example 1".

[0207] <Comparative Examples 2 to 5>

[0208] An optical film 100 was manufactured in the same manner as in Example 1, except that the type and content of filler 120 and the pH of the first mixed solution were changed, and the optical film 100 was designated as Comparative Examples 2 to 5.

[0209] [Table 1]

[0210]

[0211] In Table 1, filler 1 is a hydroxyaluminum oxide fiber filler with a diameter (A) of 4 nm, a length (B) of 1,500 nm, and a B / A of 375, and filler 2 is spherical nanoparticles with a particle size of 15 nm.

[0212] In Table 1, the molar ratio represents the molar ratio based on a total of 100 moles of diamine.

[0213] In Table 1, wt% refers to the weight percentage of the filler based on the total weight of the optical film.

[0214] <Measurement of Physical Properties>

[0215] The following physical properties of the 50-μm-thick optical films manufactured in Examples 1 to 3 and Comparative Examples 1 to 5 were measured.

[0216] (1) Measurement of True Density

[0217] Optical film samples manufactured in Examples 1 to 3 and Comparative Examples 1 to 5 with dimensions of 10 x 10 cm 2 were prepared. The optical film samples (10 x 10 cm 2 ) were cut into dimensions smaller than 1 x 1 cm 2Fragments and place the fragments together with steel balls (grinding machine) in a sample holder. Fill at least 2 / 3 of a cryogenic sample crusher (Analytical Industry, Japan, JFC-300) with liquid nitrogen, connect the sample holder containing the optical film fragments to the cryogenic sample crusher, close the chamber, pre-cool the fragments for 15 minutes, and crush the fragments using the cryogenic sample crusher for more than 15 minutes. Measure the true density of the crushed optical film sample seven times using an AccuPyc 1340 Pycnometer from Micromeritics (using helium). Determine the true density of the optical film by calculating the average of the true density values excluding the highest and lowest values from the measured true density values of the optical film.

[0218] (2) Measurement of Martens hardness (HM)

[0219] Press the optical films manufactured in Examples 1 to 3 and Comparative Examples 1 to 5 with a pyramidal diamond tip having a 90-degree diagonal according to ISO 14577-1, and measure the surface hardness based on the resulting indentation. Obtain the Martens hardness of the optical film by calculating HM = A / B, where A is the pressing load (kg) and B is the surface area (mm 2 ), and convert the result to MPa. Use an HM-2000 from Fisher Scientific International, Inc. as a Martens hardness tester to measure the Martens hardness.

[0220] - Force: 12 mN

[0221] - Running time: 12 s

[0222] - Holding time: 5 s

[0223] (3) Measurement of Vickers hardness (HV)

[0224] Press the optical films manufactured in Examples 1 to 3 and Comparative Examples 1 to 5 with a pyramidal diamond tip having a 136-degree diagonal according to ISO 14577-1, and measure the surface hardness of the resulting indentation. Obtain the Vickers hardness of the optical film by calculating HV = C / D, where C is the pressing load (kg) and D is the surface area (mm 2 ), and convert the result to MPa. Use an HM-2000 from Fisher Scientific International, Inc. as a Vickers hardness tester to measure the Vickers hardness.

[0225] - Force: 12 mN

[0226] - Running time: 12 s

[0227] - Holding time: 5 s

[0228] (4) Measurement of 1 mm indentation strength

[0229] Prepare optical film samples with dimensions of 60 x 60 cm manufactured in Examples 1 to 3 and Comparative Examples 1 to 5 respectively. 2 Place the optical film sample on a fixing device with a circular hole in the center, and then fix the sample of the optical film 100 with a clamp. Press the sample of the optical film 100 vertically at a speed of 5 mm / min with a probe having a cylindrical head with a diameter of 1.59 mm installed in a universal testing machine. The force measured when pressing from the point where a force of 1 N is applied to the probe as a reference point to a depth of 1 mm is measured as the 1 mm indentation strength of the optical film 100.

[0230] (5) Measurement of recovery rate (nIT)

[0231] Measure the recovery rate of the optical film 100 manufactured in Examples 1 to 3 and Comparative Examples 1 to 5 respectively using a nanoindenter at a temperature of 24 °C and a humidity of 40 RH%. Measure the optical film 100 at a temperature of 24 °C and a humidity of 40 RH%. Apply a load of 12 mN to the optical film 100 and press for 12 seconds, allowing the optical film 100 to rest at the maximum pressing point for 5 seconds, and measure the degree to which the optical film 100 is pressed down when the applied load is removed in the reverse direction (12 mN / 12 s / creep 5 s / 24 °C, 40 RH%).

[0232] The measurement results are shown in Table 2.

[0233] [Table 2]

[0234]

[0235] From the measurement results in Table 2, it can be seen that all the optical films 100 according to the embodiments of the present disclosure have an HM of 225 MPa or more and an HV of 46 or more, which means they have excellent surface properties. In addition, it can be seen that the 1 mm indentation strength is 10.7 N or more, indicating excellent dent resistance.

[0236] [Explanation of reference numerals]

[0237] 100: Optical film

[0238] 110: Light-transmitting matrix

[0239] 120: Filler

[0240] 200: Display device

[0241] 501: Display panel

Claims

1. An optical film, comprising: A light-transmitting matrix; And A filler dispersed in the light-transmitting matrix, Based on a thickness of 50 μm, the optical film has a 1-mm indentation strength of more than 10.7 N, Wherein, the 1-mm indentation strength refers to the force with which the optical film resists compression by a probe equipped in a universal testing machine at a rate of 5 mm / min in the vertical direction from a point where a force of 1 N is applied to a depth of 1 mm.

2. The optical film according to claim 1, wherein, The filler has a rod or fiber shape.

3. The optical film according to claim 2, wherein, The filler has a length of 1 μm to 10 μm.

4. The optical film according to claim 2, wherein, The filler has a diameter of 3 nm to 330 nm.

5. The optical film according to claim 2, wherein, The filler has an aspect ratio of 30 to 1,000, Wherein, the aspect ratio is the ratio of the length of the filler to the diameter of the filler.

6. The optical film according to claim 1, wherein, The filler includes at least one of glass fiber, aluminum-based fiber, titanium fiber, or fluoride fiber.

7. The optical film according to claim 1, wherein, The filler includes aluminum hydroxide.

8. The optical film according to claim 1, wherein, Based on the total weight of the optical film, the content of the filler is 3 wt% to 50 wt%.

9. The optical film according to claim 1, wherein The optical film has a true density of 1.55 g / cm 3 to 1.67 g / cm 3 .

10. The optical film according to claim 1, wherein, Based on a thickness of 50 μm, the optical film has an HM of 220 MPa or more, Wherein, the HM represents the Martens hardness of the optical film, The HM is measured using HM-2000 with a force of 12 mN, a running time of 12 s, and a holding time of 5 s.

11. The optical film according to claim 1, wherein, The optical film has an HV of 46 MPa or more, Wherein, the HV represents the Vickers hardness of the optical film, The HV is measured using HM-2000 with a force of 12 mN, a running time of 12 s, and a holding time of 5 s.

12. The optical film according to claim 1, wherein, The recovery rate nIT of the optical film is 60% to 100%, Wherein, the recovery rate is measured using a nanoindenter under the conditions of 12 mN / 12 s / creep 5 s / 24 °C, 40 RH%.

13. The optical film according to claim 1, wherein, The light-transmitting matrix contains at least one of imide repeating units or amide repeating units.

14. The optical film according to claim 1, wherein, The light-transmitting matrix is prepared from a polymerizable composition, the polymerizable composition comprising: A diamine monomer; and At least one of a dianhydride compound or a dicarbonyl compound.

15. The optical film according to claim 14, wherein, The diamine monomers include at least one of 2,2'-bis(trifluoromethyl)benzidine (TFDB), 4,4'-oxydianiline (ODA), p-phenylenediamine (pPDA), m-phenylenediamine (mPDA), p-methylenediamine (pMDA), m-methylenediamine (mMDA), 1,3-bis(3-aminophenoxy)benzene (133APB), 1,3-bis(4-aminophenoxy)benzene (134APB), 2,2'-bis[4(4-aminophenoxy)phenyl]hexafluoropropane (4BDAF), 2,2′-bis(3-aminophenyl)hexafluoropropane (33-6F), 2,2'-bis(4-aminophenyl)hexafluoropropane (44-6F), bis(4-aminophenyl)sulfone (4DDS), bis(3-aminophenyl)sulfone (3DDS), 1,3-cyclohexanediamine (13CHD), 1,4-cyclohexanediamine (14CHD), 2,2-bis(4-(4-aminophenoxy)phenyl)propane (6HMDA), 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (DBOH), or 4,4'-bis(3-aminophenoxy)diphenylsulfone (DBSDA).

16. The optical film according to claim 14, wherein, The dianhydride compounds include at least one of 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), pyromellitic dianhydride (1,2,4,5-benzenetetracarboxylic dianhydride, PMDA), 3,3,4,4-benzophenone tetracarboxylic dianhydride (BTDA), 4,4-oxydiphthalic anhydride (ODPA), bis(3,4-dicarboxyphenyl)dimethyl-silane dianhydride (SiDA), 4,4-bis(3,4-dicarboxyphenoxy)diphenyl sulfide dianhydride (BDSDA), sulfonyldiphthalic anhydride (SO2DPA), cyclobutane-1,2,3,4-tetracarboxylic dianhydride (CBDA), or 4,4'-(4,4′-isopropylidenediphenoxy)bis(phthalic anhydride) (6HBDA).

17. The optical film according to claim 14, wherein, The dicarbonyl compounds include at least one of terephthaloyl chloride (TPC), phthaloyl chloride, isophthaloyl chloride (IPC), diphenylisophthaloyl chloride (DPDOC), 4,4'-oxybis(benzoyl chloride) (OBBOC), naphthalene-2,3-dicarbonyl chloride, or 1,4-cyclohexanedicarbonyl chloride (CHDOC).

18. The optical film according to claim 14, wherein, The molar ratio of the dianhydride compounds to the dicarbonyl compounds is from 5:95 to 40:

60.

19. A display device, comprising: a display panel; and an optical film disposed on the display panel and according to any one of claims 1 to 18.

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