Optical film with excellent folding performance and display device including the same

Abstract

The present invention provides an optical film comprising a polymeric resin, the optical film having a yellowness index of 3.0 or less and a folding performance parameter of 1.5 GPa or less, and a display device comprising such an optical film.

Description

Technical Field

[0001] The present invention relates to an optical film containing a polymer resin having excellent folding performance and a display device including the same.

Background Art

[0002] Recently, with the thinning, lightening, and flexibilization of display devices, it has been considered to use an optical film instead of glass as a cover window. In order for an optical film to be used as a cover window of a display device, it must have excellent optical characteristics and mechanical characteristics, and also excellent folding characteristics for folding.

[0003] Therefore, it is necessary to develop a film having excellent optical characteristics and excellent mechanical characteristics such as insolubility, chemical resistance, heat resistance, radiation resistance, low-temperature characteristics, and folding characteristics.

[0004] Typically, polyimide (PI)-based resins among optical films are excellent in insolubility, chemical resistance, heat resistance, radiation resistance, and low-temperature characteristics, and are used in automotive materials, aerospace materials, spacecraft materials, insulating coating agents, insulating films, protective films, etc.

[0005] Recently, polyamide-imide-based resins obtained by adding amide repeating units to polyimide-based resins have been developed. Films manufactured using polyamide-imide-based resins are excellent in optical characteristics and mechanical characteristics such as insolubility, chemical resistance, heat resistance, radiation resistance, and low-temperature characteristics, and at the same time have excellent folding characteristics.

[0006] The amide repeating unit can be produced by polymerization of a diamine compound and a dicarbonyl compound. However, when using, for example, 2,2'-bis(trifluoromethyl)benzidine (TFDB) as the diamine, due to the rigid structure of TFDB, there is a problem that when polymerizing with a dicarbonyl compound, the dicarbonyl compound gels and the polymerization reaction does not occur sufficiently.

[0007] Therefore, even when adding a dicarbonyl compound, it is necessary to develop a polyamide-imide resin with excellent degree of polymerization.

Summary of the Invention

Problems to be Solved by the Invention

[0008] One embodiment of the present invention aims to provide an optical film containing a polymer resin with excellent folding properties.

[0009] Also, one embodiment of the present invention aims to provide an optical film with excellent optical properties and mechanical properties.

Means for Solving the Problems

[0010] One embodiment of the present invention provides an optical film containing a polymer resin, having a yellowness of 3.0 or less, and a folding performance parameter calculated by the following formula 1 of 1.5 GPa or less.

[0011] <Formula 1> JPEG0007714693000001.jpg1591

[0012] In the above formula 1, R is the radius of curvature of the optical film at the folding center line during folding, which is 0.5 mm, d is the thickness of the optical film, and the unit of thickness is μm, and E' is the elastic deformation index calculated by the following formula 2. However, in the above formula 1, for the radius of curvature and the thickness, only numbers are substituted excluding the units.

[0013] <Formula 2> Elastic deformation index (E') = E / (1 - v 2 )

[0014] In the above formula 2, E is the modulus of the optical film, the unit of the modulus is GPa, and v is the Poisson's ratio of the optical film.

[0015] The elastic deformation index (E') calculated by the above formula 2 can be 5.5 or more.

[0016] The polymer resin can contain an imide repeating unit and an amide repeating unit.

[0017] The amide repeating unit can be included at a ratio of 80% or more with respect to the number of the imide repeating unit and the amide repeating unit.

[0018] The imide repeating unit can contain a first repeating unit and a second repeating unit.

[0019] The amide repeating unit can contain a third repeating unit and a fourth repeating unit.

[0020] The first repeating unit is an imide repeating unit obtained by the polymerization reaction of a first diamine compound and a first dianhydride compound, and the second repeating unit can be an imide repeating unit obtained by the polymerization reaction of a second diamine compound and a second dianhydride compound.

[0021] The third repeating unit is an amide repeating unit obtained by the polymerization reaction of a first diamine compound and a first dicarbonyl compound, and the fourth repeating unit can be an amide repeating unit obtained by the polymerization reaction of a second diamine compound and a second dicarbonyl compound.

[0022] The first diamine compound may be 2,2'-bis(trifluoromethyl)benzidine (TFDB).

[0023] The second diamine compound may be a diamine compound containing one or more functional groups selected from the group consisting of a sulfonyl group, a carbonyl group, a methylene group, a propylene group, and a halogen element.

[0024] The second diamine compound may contain at least one selected from the group consisting of bis(3-aminophenyl)sulfone (3DDS), bis(4-aminophenyl)sulfone (4DDS), 2,2-bis(3-aminophenyl)hexafluoropropane (3,3'-6F), 2,2-bis(4-aminophenyl)hexafluoropropane (4,4'-6F), 4,4'-methylenedianiline (MDA), 3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone, and tetrachloridebenzidine (CIBZ).

[0025] The molar ratio of the polymerized first diamine compound to the second diamine compound may be 95:5 to 50:50.

[0026] The polymer resin may have a weight-average molecular weight (Mw) of 200,000 to 500,000.

[0027] Another embodiment of the present invention provides a display device including a display panel; and an optical film according to any one of claims 1 to 13 disposed on the display panel.

Advantages of the Invention

[0028] According to one embodiment of the present invention, an optical film excellent in folding characteristics is to be provided.

[0029] Since the optical film according to another embodiment of the present invention has excellent optical and mechanical properties, when used as a cover window of a display device, it can effectively protect the display surface of the display device.

Brief Description of the Drawings

[0030]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0031] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the embodiments described below are presented for illustrative purposes to assist in a clear understanding of the present invention and do not limit the scope of the present invention.

[0032] The shapes, sizes, ratios, angles, numbers, etc. disclosed in the drawings for explaining the embodiments of the present invention are illustrative, and thus the present invention is not limited to the matters illustrated in the drawings. Throughout the specification, the same components may be referred to by the same reference numerals. When it is determined that a detailed description of related known technologies may unnecessarily impair the gist of the present invention in explaining the present invention, the detailed description thereof is omitted.

[0033] When terms such as "including", "having", "comprising" and the like mentioned in this specification are used, other parts may be added unless the expression "only" is used. When a component is expressed in the singular, it includes a plurality unless otherwise explicitly stated. Also, when interpreting a component, it should be interpreted to include an error range even without a separate explicit statement.

[0034] In the case of an explanation of a positional relationship, for example, when the positional relationship between two parts is explained by "on", "above", "below", "beside" or the like, one or more other parts may be located between the two parts unless the expressions "immediately" or "directly" are used.

[0035] Spatially relative terms such as "below", "beneath", "lower", "above", "upper" etc. can be used to easily describe the correlation between one element or component and another element or component as shown in the drawings. Spatially relative terms should be understood as terms including different directions of elements during use or operation in addition to the directions shown in the drawings. For example, when an element shown in the drawings is inverted, an element described as "below" or "beneath" another element can be placed "above" the other element. Therefore, the exemplary term "below" can include all directions of below and above. Similarly, the exemplary term "above" can include all directions of above and below.

[0036] In the case of an explanation of a temporal relationship, for example, when a temporal sequence is explained by "after", "subsequent to", "next", "before" or the like, it can include cases that are not continuous unless the expressions "immediately" or "directly" are used.

[0037] The terms "first", "second", etc. are used to describe various components, but these components are not limited by these terms. These terms are merely used to distinguish one component from another. Therefore, the first component referred to below may be the second component in the technical concept of the present invention.

[0038] The term "at least one" should be understood to include all combinations that can be presented from one or more related items. For example, the meaning of "at least one of the first item, the second item, and the third item" can mean not only each of the first item, the second item, or the third item alone, but also all combinations of items that can be presented from two or more of the first item, the second item, and the third item.

[0039] Regarding the respective features of various embodiments of the present invention, they can be partially or wholly combined or combined with each other, various linkages and drives are technically possible, and each embodiment may be implemented independently of each other, and there may also be a case where they are implemented together as an associated relationship.

[0040] One embodiment of the present invention provides an optical film. The optical film according to one embodiment of the present invention contains a polymer resin.

[0041] The polymer resin can be included in various shapes and forms, such as in the form of solid powder in the film, in the form of being dissolved in a solution, or in the form of a solidified matrix after being dissolved in a solution and then solidified. As long as it is a resin containing the same repeating unit as the present invention, regardless of its shape and form, it can all be regarded as the same polymer resin of the present invention. However, generally, in the film, the polymer resin can exist in the form of a matrix solidified after drying the applied polymer resin solution.

[0042] According to one embodiment of the present invention, the optical film has a folding performance parameter of the optical film calculated by the following formula 1 of 1.5 GPa or less.

[0043] <Formula 1> JPEG0007714693000002.jpg1591

[0044] In Formula 1, R is the radius of curvature of the optical film at the folding center line during folding and is 0.5 mm, d is the thickness of the optical film and the unit of thickness is μm, and E' is the elastic deformation index calculated by the following Formula 2. The thickness of the optical film can be measured using an electronic micrometer, for example, the electronic micrometer of Anritsu Corporation. The radius of curvature of the optical film can be measured using a bending cycle evaluation device, for example, DLDM111LHA of YUASA Corporation. After folding inside the device, the gap between the internal folding parts can be confirmed with a gap gauge and measured. However, in Formula 1, for the radius of curvature and the thickness, only numbers are substituted excluding the units.

[0045] <Formula 2> Elastic deformation index (E') = E / (1 - v 2 )

[0046] In Formula 2, E is the modulus of the optical film and the unit of the modulus is GPa, and v is the Poisson's ratio of the optical film.

[0047] The modulus of the optical film can be measured using a universal material testing machine (for example, INSTRON) under the following conditions based on the standard specification ASTM D882.

[0048] -25°C / 50RH% - Load Cell 30KN, Grip 250N. - Specimen size 10X50 mm, tensile speed 25 mm / min

[0049] The Poisson's ratio of the optical film is the ratio of the lateral strain to the axial strain of a specimen under axial load, and it can be measured by a non-contact (Video extensometer) method based on the standard specification ASTM E-132. Specifically, it can be measured under the following conditions using a universal material testing machine (for example, Instron 3367 of Instron).

[0050] - Test speed: 10 mm / min -(25±2)°C / (45±5)%RH

[0051] The folding performance parameters of the present invention will be described in more detail with reference to the drawings. FIG. 1 is a cross-sectional view of an optical film showing the change in length during folding of the optical film. FIG. 1 is merely one example for showing the change in length during folding of the optical film, and the change in length during folding may have different forms for each optical film. Therefore, the present invention is not limited thereto.

[0052] When the folding performance parameter of the optical film is 1.5 GPa or less, the resistance force generated during folding becomes small, so that excellent folding performance can be exhibited, and folding traces may not occur (no creases). The smaller the radius of curvature (R), the more the occurrence of folding traces (creases) increases. However, when the "folding performance parameter" is 1.5 GPa or less, the folding performance is excellent and no folding traces occur. In particular, the radius of curvature (R) in the "folding performance parameter" is 0.5 mm. When the "folding performance parameter" is 1.5 GPa or less, even when folding with a radius of curvature (R) of 0.5 mm, no folding traces occur and excellent folding performance can be achieved.

[0053] Specifically, when the optical film is folded, mechanical changes in the film may occur. The folding trace (crease) in the present invention refers to, for example, the phenomenon that the film is bent, or uneven wrinkles occur on the surface of the film, or white turbidity occurs in the transparent film. In addition to the occurrence of wrinkles or turbidity, a difference in length may occur before and after folding, or mechanical and optical property changes of the optical film such as a difference in light transmittance can be included.

[0054] When the optical film is folded, stress is applied to the film. At this time, depending on the folding direction, compressive stress is applied to the inner surface (hereinafter referred to as "inner diameter") of the fold of the optical film, and tensile stress is applied to the outer surface (hereinafter referred to as "outer diameter") of the fold, which is the opposite surface. Accordingly, compressive strain occurs in the folding inner diameter of the optical film, and tensile strain occurs in the folding outer diameter.

[0055] Specifically, as shown in FIG. 1, before folding, the distance between two points (a, b) on the folding inner diameter is the same as the distance between two points (c, d) on the outer diameter. However, when the optical film is folded, the two points a and b on the folding inner diameter of the optical film are deformed to a' and b' by the compressive stress during folding, and the two points c and d on the folding outer diameter are deformed to c' and d' by the tensile stress during folding. Due to the compressive stress on the folding inner diameter, the distance between a' and b' is reduced compared to the distance between a and b, and the distance between c' and d' on the folding outer diameter is increased compared to the distance between c and d. At this time, the radius of curvature (R1) of the folding inner diameter is "R - d / 2" based on the center line (M) of the optical film, and the radius of curvature (R2) of the folding outer diameter is "R + d / 2" based on the center line (M) of the optical film. Based on the radii of curvature of the folding inner diameter and the folding outer diameter, the calculated distance between a' and b' (L 1 ) is π(R - d / 2), and the distance between c' and d' (L2 ) is π(R + d / 2).

[0056] The compressive stress and tensile stress are proportional to the magnitude of the deformed length. The deformed length of the outer diameter is +π(d / 2), and the deformed length of the inner diameter is -π(d / 2). Therefore, the force (stress) applied to the inner diameter is proportional to d / 2R (= [π(d / 2)] / πR), and the force (stress) applied to the outer diameter is proportional to d / 2R. The smaller the forces applied to the outer and inner diameters, the more the folding performance of the optical film can be improved. Therefore, the smaller the value of d / 2R of the optical film, the more advantageous it is for folding. Specifically, when d / 2R is 0.08 or less, the folding performance of the optical film is excellent and no folding marks occur. When it exceeds 0.08, excessive pressure is applied during folding, and folding marks (creases) may occur after folding.

[0057] Also, the folding performance parameter of the optical film is proportional to the elastic deformation index (E'). The larger the elastic deformation index (E'), the more the folding performance of the optical film is improved, and the smaller the elastic deformation index (E'), the more the folding performance of the optical film decreases.

[0058] According to an embodiment of the present invention, the optical film may have an elastic deformation index (E') calculated by the above formula 2 of 5.5 GPa or more. The folding performance of the optical film can be improved by adjusting not only the film thickness and radius of curvature but also the modulus and Poisson's ratio of the optical film. As the modulus and Poisson's ratio of the optical film increase, the resistance to deformation of the optical film during folding increases. For example, even if the thickness of the optical film increases, if the modulus of the optical film increases, the folding performance can be improved. On the other hand, even if the thickness of the optical film decreases, if the modulus of the optical film also decreases, the folding performance deteriorates and it becomes unsuitable for use as a cover window of a flexible display device. Also, when the Poisson's ratio of the optical film increases, the folding performance can be improved, and conversely, when the Poisson's ratio of the optical film decreases, the folding performance deteriorates.

[0059] According to an embodiment of the present invention, the optical film may have a yellowness index (Y.I.) of 3.0 or less. The yellowness index can be measured using a Spectrophotometer (CM-3700D, KONICA MINOLTA) according to the standard specification ASTM E313.

[0060] According to an embodiment of the present invention, the optical film may include a polymer resin.

[0061] The optical film can have a folding performance parameter of 1.5 GPa or less by adjusting the components and content of the repeating unit of the polymer resin. Also, by improving the degree of polymerization of the polymer resin, the folding performance parameter can be decreased and the folding performance can be improved.

[0062] The polymer resin can contain at least one of imide repeating units and amide repeating units. For example, the polymer resin can contain imide repeating units or amide repeating units, and can also contain both imide repeating units and amide repeating units. The polymer resin may be at least one of polyimide resins, polyamide resins, and polyamide-imide resins.

[0063] In the present invention, the imide repeating units of the polymer resin can be produced from monomer components containing diamine compounds and dianhydride compounds. The diamine compound and the dianhydride compound can be subjected to a polymer polymerization reaction to form an amic acid, and the amic acid can be imidized again to form imide repeating units. Also, the amide repeating units can be produced by polymer polymerization from monomer components containing diamine compounds and dicarbonyl compounds. The specific structures of the imide repeating units and the amide repeating units can vary depending on the monomers to be reacted.

[0064] However, the polymer resin according to an embodiment of the present invention is not limited thereto. The polymer resin according to an embodiment of the present invention can be produced from monomer components that further contain other compounds in addition to diamine compounds, dianhydride compounds, and dicarbonyl compounds. Therefore, the polymer resin according to an embodiment of the present invention can further have other repeating units in addition to imide repeating units and amide repeating units.

[0065] The optical film according to an embodiment of the present invention can contain at least one of polyimide resins, polyamide resin systems, and polyamide-imide resins.

[0066] According to one embodiment of the present invention, the optical film may be any one of a polyimide-based film, a polyamide-based film, and a polyamide-imide-based film. However, one embodiment of the present invention is not limited thereto, and any film having light transmissivity can be an optical film according to one embodiment of the present invention.

[0067] According to one embodiment of the present invention, the polymer resin can contain amide repeating units at a ratio of 80% or more with respect to the total number of imide repeating units and amide repeating units. Preferably, the number of amide repeating units can be contained at a ratio of 95% or more with respect to the total number of imide and amide repeating units. More preferably, it can be contained at a ratio of 98% or more.

[0068] When the polymer resin contains amide repeating units at a ratio of 80% or more with respect to the number of imide and amide repeating units, when manufacturing an optical film with the polymer resin, the optical properties of the film can be maintained and the mechanical properties can be improved. In particular, the folding performance of the optical film can be significantly improved. That is, by containing a larger amount of amide repeating units than imide repeating units, a film that is colorless and transparent, excellent in insolubility, chemical resistance, heat resistance, radiation resistance, and low-temperature characteristics, and excellent in folding performance can be manufactured.

[0069] However, when adding a large amount of dicarbonyl-based compounds in order to contain a large amount of amide repeating units, there is a problem that the dicarbonyl-based compounds gel and a sufficient polymerization reaction does not occur.

[0070] The present invention can reduce and prevent the gelation of dicarbonyl-based compounds by performing a polymerization reaction using two or more diamine-based compounds.

[0071] According to one embodiment of the present invention, the imide repeating unit can include a first repeating unit and a second repeating unit.

[0072] The imide repeating unit is formed by the polymerization reaction of a diamine compound and a dianhydride compound. The first repeating unit is an imide repeating unit formed by the polymerization reaction of a first diamine compound and a first dianhydride compound, and the second repeating unit is an imide repeating unit formed by the polymerization reaction of a second diamine compound and a second dianhydride compound. The polymer resin of the present invention contains a first diamine compound and a second diamine compound, and contains repeating units derived from at least two or more diamine compounds.

[0073] Specifically, according to an embodiment of the present invention, the first diamine compound can be 2,2'-bis(trifluoromethyl)benzidine (TFDB). According to an embodiment of the present invention, the second diamine compound can include other aromatic diamine compounds other than TFDB. The imide repeating unit and the amide repeating unit of the present invention can be derived from TFDB; and other aromatic diamine compounds other than TFDB.

[0074] Since 2,2'-bis(trifluoromethyl)benzidine (TFDB) has a unique linear and rigid structure, when it contains repeating units derived from TFDB, it is excellent in improving mechanical properties such as film insolubility, chemical resistance, heat resistance, radiation resistance, and low-temperature properties.

[0075] However, due to the rigid structure of 2,2'-bis(trifluoromethyl)benzidine (TFDB), when reacting with dicarbonyl compounds, the polymerization reaction proceeds rapidly. Due to the rapid polymerization reaction, only some of the dicarbonyl compounds react with the diamine compound, and the other dicarbonyl compounds may gel without undergoing the polymerization reaction. Gelation of the dicarbonyl compound can reduce the degree of polymerization of the resin and inhibit the optical properties of the film. Therefore, it is difficult to produce a polymer resin containing a large amount of amide repeating units by adding only 2,2'-bis(trifluoromethyl)benzidine (TFDB). The present invention can prevent gelation of the dicarbonyl compound and improve the degree of polymerization of the polymer by using a second diamine compound.

[0076] According to an embodiment of the present invention, the second diamine compound includes an aromatic diamine compound.

[0077] In one embodiment of the present invention, the "aromatic diamine compound" means a diamine compound in which an amino group is directly bonded to an aromatic ring, and may include an aliphatic group or other substituents in a part of its structure. The aromatic ring may be a single ring or a fused ring in which single rings are directly or linked by heteroatoms, or a condensed ring. The aromatic ring can include, for example, a benzene ring, a biphenyl ring, a naphthalene ring, an anthracene ring, and a fluorene ring, but is not limited thereto.

[0078] According to an embodiment of the present invention, the second diamine compound can be represented by the following Chemical Formula 1.

[0079]

Chemical Formula

[0080] In Chemical Formula 1, A 1 represents a divalent aromatic organic group. The aromatic organic group refers to an organic group in which single bonds (single bonds) and double bonds are alternately linked to form a ring, and π electrons are delocalized. For example, A 1It contains a divalent aromatic organic group having 4 to 40 carbon atoms. The hydrogen atoms in the aromatic organic group contained in Chemical Formula 1 can be substituted by a halogen element, a hydrocarbon group, or a hydrocarbon group substituted by a halogen element. The carbon number of the hydrocarbon group substituted with a hydrogen atom or the hydrocarbon group substituted by a halogen element can be 1 to 8. For example, A 1 The hydrogen contained in can be substituted with -F, -CH3, -CF3, etc.

[0081] An optical film produced using a diamine compound in which a hydrogen atom is substituted with a hydrocarbon group substituted with a fluorine can have excellent light transmittance and excellent processing characteristics.

[0082] A of Chemical Formula 1 1 can include, for example, a structure represented by any one of the following structural formulas.

[0083] JPEG0007714693000004.jpg28141

[0084] In the above structural formula, * indicates the bonding position. In the above structural formula, X may independently be any one of a single bond, O, S, SO2, CO, CH2, C(CH3)2, and C(CF3)2. The bonding position of X to each ring is not particularly limited, but the bonding position of X can be, for example, the meta or para position with respect to each ring.

[0085] According to an embodiment of the present invention, the second diamine compound may contain one or more functional groups selected from the group consisting of a sulfonyl group, a carbonyl group, a methylene group, a propylene group, and a halogen element.

[0086] The substituents of sulfonyl group, carbonyl group, methylene group, propylene group and halogen element play a role in regulating the electron transfer within the compound. Therefore, by including at least one of the substituents of sulfonyl group, carbonyl group, methylene group, propylene group and halogen element, the second diamine-based compound can regulate the ionization energy. Thereby, the reactivity and reaction rate of the polymerization reaction with the dicarbonyl-based compound can be appropriately regulated.

[0087] According to one embodiment of the present invention, the second diamine-based compound may include any one or more selected from the group consisting of bis(3-aminophenyl)sulfone (3DDS), bis(4-aminophenyl)sulfone (4DDS), 2,2-bis(3-aminophenyl)hexafluoropropane (2,2-Bis(3-aminophenyl)hexafluoropropane, 3,3'-6F), 2,2-bis(4-aminophenyl)hexafluoropropane (2,2-Bis(4-aminophenyl)hexafluoropropane, 4,4'-6F), 4,4'-methylenedianiline (4,4'-Methylenedianiline, MDA), 3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone and tetrachloridebenzidine (CIBZ).

[0088] According to an embodiment of the present invention, the first dianhydride-based compound and the second dianhydride-based compound can each independently be represented by the following Chemical Formula 2. The first dianhydride-based compound and the second dianhydride-based compound may be the same as each other or may be different compounds from each other. The present invention is not limited thereto.

[0089]

Chemical formula

[0090] In Chemical Formula 2, A 2 represents a tetravalent organic group. For example, A 2 can include a tetravalent organic group having 4 to 40 carbon atoms. A hydrogen atom in the organic group contained in Chemical Formula 2 can be substituted with a halogen element, a hydrocarbon group, or a halogen-substituted hydrocarbon group. Here, the carbon number of the hydrocarbon group or the halogen-substituted hydrocarbon group substituted for the hydrogen atom can be 1 to 8.

[0091] A in Chemical Formula 2 2 can include, for example, a structure represented by any one of the following structural formulas.

[0092] JPEG0007714693000006.jpg65141

[0093] In the above structural formula, * indicates the bonding position. In the above structural formula, Z may independently be any one of a single bond, O, S, SO2, CO, (CH2)n, (C(CH3)2)n, and (C(CF3)2)n, and n may be an integer of 1 to 5. The bonding position of Z to each ring is not particularly limited, but the bonding position of Z can be, for example, the meta or para position with respect to each ring.

[0094] According to an embodiment of the present invention, the first dianhydride-based compound and the second dianhydride-based compound are each independently 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA), biphenyl tetracarboxylic dianhydride (BPDA), naphthalene tetracarboxylic dianhydride (NTDA), diphenyl sulfone tetracarboxylic dianhydride (DSDA), 4-(2,5-oxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic anhydride (TDA), pyromellitic dianhydride (PMDA), benzophenone tetracarboxylic dianhydride (BTDA), oxydiphthalic anhydride (ODPA), bis(carboxyphenyl)dimethyl silane dianhydride (SiDA), bis(dicarboxyphenoxy)diphenyl sulfide dianhydride (BDSDA), sulfonyldiphthalic anhydride,It can contain any one or more selected from the group consisting of SO2DPA) and isopropylidene diphenoxy bis phthalic anhydride (BPADA).

[0095] The optical film according to an embodiment of the present invention can contain a plurality of dianhydride compounds.

[0096] An optical film produced using a dianhydride compound substituted with a hydrocarbon group in which a hydrogen atom is fluorine-substituted can have excellent light transmittance and excellent processing characteristics.

[0097] According to an embodiment of the present invention, the amide repeating unit can include a third repeating unit and a fourth repeating unit.

[0098] The amide repeating unit is formed by a polymerization reaction of a diamine compound and a dicarbonyl compound. The third repeating unit is an amide repeating unit formed by a polymerization reaction of a first diamine compound and a first dicarbonyl compound, and the fourth repeating unit is an amide repeating unit formed by a polymerization reaction of a second diamine compound and a second dicarbonyl compound.

[0099] According to an embodiment of the present invention, the first dicarbonyl compound and the second dicarbonyl compound can each independently be represented by the following Chemical Formula 3. The first dicarbonyl compound and the second dicarbonyl compound may be the same as each other or different compounds from each other. The present invention is not limited thereto.

[0100]

Chemical formula

[0101] In Chemical Formula 3, A 3 represents a divalent organic group. For example, A 3It can contain a divalent organic group having 4 to 40 carbon atoms. The hydrogen atoms in the organic group contained in Chemical Formula 3 can be substituted with a halogen element, a hydrocarbon group, or a fluorine-substituted hydrocarbon group. Here, the hydrocarbon group or the fluorine-substituted hydrocarbon group in which the hydrogen atom is substituted can have 1 to 8 carbon atoms. For example, A 3 The hydrogen contained in can be substituted with -F, -CH3, -CF3, etc.

[0102] A in Chemical Formula 3 3 can contain a structure represented by any one of the following structural formulas, for example.

[0103] JPEG0007714693000008.jpg44141

[0104] In the above structural formula, * indicates the bonding position. In the above structural formula, Y can independently be any one of a single bond, O, S, SO2, CO, CH2, C(CH3)2, and C(CF3)2. The bonding position of Y to each ring is not particularly limited, but the bonding position of Y can be, for example, the meta or para position with respect to each ring.

[0105] According to an embodiment of the present invention, the first dicarbonyl compound and the second dicarbonyl compound may each independently contain any one or more selected from the group consisting of terephthaloyl chloride (TPC), isophthaloyl dichloride (IPC), biphenyl dicarbonyl chloride (BPDC), 4,4'-oxybis benzoyl chloride (OBBC), and naphthalene dicarbonyl dichloride (NTDC).

[0106] According to an embodiment of the present invention, the ratio of the number of the first repeating units and the third repeating units to the number of the second repeating units and the fourth repeating units can be 95:5 to 50:50. The first repeating units and the third repeating units are all repeating units in which all of the first diamine compounds participated in the polymerization reaction, and the second repeating units and the fourth repeating units are all repeating units in which all of the second diamine compounds participated in the polymerization reaction. Therefore, the molar ratio of the first diamine compound to the second diamine compound participating in the polymerization reaction is 95:5 to 50:50.

[0107] When the number of the first repeating units and the third repeating units is larger than when the ratio of the number of the first repeating units and the third repeating units to the number of the second repeating units and the fourth repeating units is 95:5, the haze of the film may increase due to the increase in the ratio of the repeating units derived from TFDB and the dicarbonyl compound. On the other hand, when the number of the second repeating units and the fourth repeating units is larger than 50:50, the heat resistance and strength of the film may decrease.

[0108] The polymer resin according to an embodiment of the present invention may include a first repeating unit represented by the following Chemical Formula 4 and a second repeating unit represented by the following Chemical Formula 5.

[0109]

Chemical formula

[0110] A included in Chemical Formula 4 2 is as already described.

[0111]

Chemical formula

[0112] A included in Chemical Formula 5 1 and A 2 is as already described.

[0113] The polymer resin according to an embodiment of the present invention may include a third repeating unit represented by the following chemical formula 6 and a fourth repeating unit represented by the following chemical formula 7.

[0114]

Chem.

[0115] A contained in Chemical Formula 6 3 is as already described.

[0116]

Chem.

[0117] A contained in Chemical Formula 7 1 and A 3 are as already described.

[0118] According to an embodiment of the present invention, the weight-average molecular weight (Mw) of the polymer resin of the present invention can be 200,000 to 500,000.

[0119] The weight-average molecular weight of the polymer resin can be measured using GPC (Alliance e2695 / 2414 RID, waters) under the following conditions.

[0120] Detector: 2414 RID, Waters Mobile phase: 10 mM LiBr in DMAc Sample concentration: 0.25 (w / w)% in DMAc Column and detector temperature: 50°C Flow Rate: 1.0 ml / min

[0121] The dicarbonyl compound reduces the degree of polymerization of the polymer resin containing a large amount of amide repeating units due to the rapid reaction rate with the diamine compound, especially with TFDB. The weight average molecular weight is in a proportional relationship with the degree of polymerization, and when the degree of polymerization decreases, the weight average molecular weight of the polymer resin also decreases accordingly.

[0122] When the weight average molecular weight of the polymer resin is less than 200,000, the degree of polymerization decreases, the number of terminal groups of the polymer chain increases, and the physical properties of the polymer resin deteriorate. On the other hand, it is difficult in terms of process to produce a polymer resin with a weight average molecular weight exceeding 500,000. During polymerization, the polymer resin adjusts the weight average molecular weight by controlling the polymerization viscosity. However, when the weight average molecular weight of the resin exceeds 500,000, the polymerization viscosity is extremely high, the fluidity of the reaction solution decreases, making control and processing difficult. Also, when the polymer resin is redissolved, a large amount of solvent is required, which is disadvantageous in terms of process.

[0123] According to an embodiment of the present invention, the optical film has light transmissivity. Also, the optical film has flexible characteristics. For example, the optical film has bending characteristics, folding characteristics, and rollable characteristics. The optical film can have excellent mechanical and optical properties.

[0124] According to an embodiment of the present invention, the optical film can have a thickness sufficient for the optical film to protect the display panel. For example, the optical film can have a thickness of 10 to 100 μm.

[0125] According to an embodiment of the present invention, the optical film can have an average light transmittance of 88% or more in the visible light region measured by a UV spectrophotometer with a reference thickness of 50 μm.

[0126] The average light transmittance of the optical film can be measured at wavelengths of 360 to 740 nm using a spectrophotometer (Spectrophotometer; CM - 3700D, KONICA MINOLTA).

[0127] According to one embodiment of the present invention, the optical film can have a haze of 0.5% or less based on a thickness of 50 μm.

[0128] The haze of the optical film can be measured by cutting the manufactured optical film into 50 mm Х 50 mm, measuring it five times according to ASTM D1003 using a haze meter (model name: HM-150) manufactured by Murakami, and taking the average value as the haze of the optical film.

[0129] FIG. 2 is a cross-sectional view of a part of a display device (200) according to still another embodiment of the present invention, and FIG. 3 is an enlarged cross-sectional view of the "P" part of FIG. 2.

[0130] Referring to FIG. 2, a display device (200) according to another embodiment of the present invention includes a display panel (501) and an optical film (100) on the display panel (501).

[0131] Referring to FIGS. 2 and 3, the display panel (501) includes a substrate (510), thin film transistors (TFTs) on the substrate (510), and organic light emitting elements (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 FIGS. 2 and 3 is an organic light emitting display device.

[0132] The substrate (510) can be made of glass or plastic. Specifically, the substrate (510) can be made of plastic such as a polymer resin or an optical film. Although not shown, a buffer layer can be disposed on the substrate (510).

[0133] The thin film transistor (TFT) is disposed 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 at least a part 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).

[0134] Referring to FIG. 3, a gate insulating film (535) is disposed between the gate electrode (530) and the semiconductor layer (520). An interlayer insulating film (551) is disposed on the gate electrode (530), and the source electrode (541) and the source electrode (541) can be disposed on the interlayer insulating film (551).

[0135] The planarization film (552) is disposed on the thin film transistor (TFT) and planarizes the upper part of the thin film transistor (TFT).

[0136] The first electrode (571) is disposed on the planarization film (552). The first electrode (571) is connected to the thin film transistor (TFT) through a contact hole provided in the planarization film (552).

[0137] The bank layer (580) is disposed on a part of the first electrode (571) and the planarization film (552) and defines a pixel region or a light emitting region. For example, by disposing the bank layer (580) in a matrix structure in a boundary region between a plurality of pixels, the pixel region can be defined by the bank layer (580).

[0138] The organic light emitting layer (572) is disposed on the first electrode (571). The organic light emitting layer (572) can also be disposed on the bank layer (580). The organic light emitting layer (572) can include one light emitting layer or can include two light emitting layers stacked one on top of the other. In such an organic light emitting layer (572), light having any one of the colors red, green, and blue can be emitted, or white light can be emitted.

[0139] The second electrode (573) is disposed on the organic light-emitting layer (572).

[0140] The first electrode (571), the organic light-emitting layer (572), and the second electrode (573) can be laminated to form an organic light-emitting element (270).

[0141] Although not shown, when the organic light-emitting layer (572) emits white light, each individual pixel can include a color filter for filtering the white light emitted from the organic light-emitting layer (572) by wavelength. The color filter is formed on the light traveling path.

[0142] A thin film encapsulation layer (590) can be disposed on the second electrode (573). The thin film encapsulation layer (590) can include at least one organic film and at least one inorganic film, and the at least one organic film and the at least one inorganic film can be alternately disposed.

[0143] An optical film (100) is disposed on the display panel (501) having the laminated structure described above.

[0144] Hereinafter, a method for manufacturing an optical film according to another embodiment of the present invention will be briefly described.

[0145] The method for manufacturing an optical film of the present invention includes the steps of preparing a polymer resin; dissolving the polymer resin in a solvent to produce a polymer resin solution; and manufacturing an optical film using the polymer resin solution.

[0146] The step of preparing the polymer resin can be obtained by polymerizing monomers for forming the polymer resin through a polymerization reaction.

[0147] According to another embodiment of the present invention, the polymer resin can be produced from monomer components including a first diamine compound, a second diamine compound, a first dianhydride compound, a second dianhydride compound, a first dicarbonyl compound, and a second dicarbonyl compound. The present invention is not limited by the addition order and method of the monomers. For example, the first and second dianhydride compounds and the first and second dicarbonyl compounds can be sequentially added to a solution in which the first and second diamine compounds are dissolved for a polymerization reaction. Alternatively, in order to remove randomness, the first diamine compound, the first and second dianhydride compounds, the second diamine compound, and the first and second dicarbonyl compounds can be added in this order, or the second diamine compound, the first and second dianhydride compounds, the first diamine compound, and the first and second dicarbonyl compounds can be added in this order for a polymerization reaction.

[0148] More specifically, the polymer resin can be produced by a polymerization reaction and imidization of monomers including a first diamine compound, a second diamine compound, a first and second dianhydride compounds, and a first and second dicarbonyl compounds. By the polymerization reaction and imidization of monomers including the first and second diamine compounds and the first and second dianhydride compounds, an imide repeating unit can be produced. Also, by the polymerization reaction of monomers including the first and second diamine compounds and the first and second dicarbonyl compounds, an amide repeating unit can be produced.

[0149] Therefore, the polymer resin according to another embodiment of the present invention can have an imide repeating unit and an amide repeating unit.

[0150] The imide repeating unit and the amide repeating unit can be copolymerized after being separately manufactured, or after manufacturing the imide repeating unit first, a dicarbonyl compound can be further added for the production of the amide repeating unit, or after manufacturing the amide repeating unit first, a dianhydride compound can be further added for the production of the imide repeating unit. The polymer resin of the present invention is not limited by the production order of the repeating units (the addition order of the monomers).

[0151] According to another embodiment of the present invention, the first and second dicarbonyl compounds can be added in an amount of 80 mol% or more based on the combined molar amount of the first and second dianhydride compounds and the first and second dicarbonyl compounds. Thereby, the polymer resin of the present application comes to contain an amide repeating unit in a ratio of 80% or more. Preferably, the first and second dicarbonyl compounds can be added in an amount of 95 mol% or more based on the combined molar amount of the first and second dianhydride compounds and the first and second dicarbonyl compounds, and more preferably, in an amount of 98 mol% or more.

[0152] According to another embodiment of the present invention, the first diamine compound is 2,2'-bis(trifluoromethyl)benzidine (TFDB).

[0153] According to another embodiment of the present invention, the second diamine compound contains an aromatic diamine compound. Hereinafter, in order to avoid duplication, the description of the components already described will be omitted.

[0154] As the first diamine compound, 2,2'-Bis(trifluoromethyl)benzidine (TFDB) can be used. As the second diamine compound, the aromatic diamine compound of Chemical Formula 1 described above can be used. As the first and second dianhydride compounds, the compound of Chemical Formula 2 described above can be used. As the first and second dicarbonyl compounds, the compound of Chemical Formula 3 described above can be used.

[0155] According to another embodiment of the present invention, the aromatic diamine compound of the second diamine compound can contain one or more functional groups selected from the group consisting of a sulfonyl group, a carbonyl group, a methylene group, a propylene group, and a halogen element.

[0156] According to another embodiment of the present invention, the aromatic diamine compound of the second diamine compound can contain any one or more selected from the group consisting of Bis(3-aminophenyl)sulfone (3DDS), Bis(4-aminophenyl)sulfone (4DDS), 3,3'-6F (2,2-Bis(3-aminophenyl)hexafluoropropane), 4,4'-6F (2,2-Bis(4-aminophenyl)hexafluoropropane), MDA (4,4'-Methylenedianiline), 3,3'-CO (3-(Dimethylamino)benzophenone), 4,4'-CO (4-(Dimethylamino)benzophenone), and CIBZ (Tetrachloridebenzidine).

[0157] According to another embodiment of the present invention, the ratio of the addition amounts of the first diamine compound and the second diamine compound can be 95:5 to 50:50.

[0158] According to another embodiment of the present invention, in the step of manufacturing the polymer resin solution, the solvent can be, for example, an aprotic polar organic solvent such as dimethylacetamide (DMAc, N,N-dimethylacetamide), dimethylformamide (DMF, N,N-dimethylformamide), 1-methyl-2-pyrrolidinone (NMP), m-cresol, tetrahydrofuran (THF), chloroform, methyl ethyl ketone (MEK), etc., and mixtures thereof. However, an embodiment of the present invention is not limited thereto, and other known solvents can also be used.

[0159] Hereinafter, the present invention will be described more specifically with reference to exemplary embodiments. However, the present invention is not limited by the production examples and embodiments described below.

[0160] <Example 1> A 500 mL reactor equipped with a stirrer, a nitrogen injection device, a dropping funnel, a temperature regulator, and a cooler was filled with 313.34 g of DMAc (N,N-Dimethylacetamide) while passing nitrogen through it. After adjusting the temperature of the reactor to 25°C, 24.02 g (0.075 mol) of TFDB as the first diamine compound was dissolved, and 6.21 g (0.025 mol) of 3DDS (Bis(3-aminophenyl)sulfone) as the second diamine compound was additionally dissolved, and this solution was maintained at 25°C. After dissolving the diamine compounds, 0.89 g (0.002 mol) of 6FDA was added here and stirred for 2 hours to completely dissolve 6FDA. After lowering the temperature of the reactor to 10°C, 19.90 g (0.098 mol) of TPC (Terephthaloyl Chloride) was added, completely dissolved and reacted for 1 hour, and then the temperature was raised to 25°C. 0.35 g of pyridine and 0.45 g of acetic anhydride were added here, stirred at 80°C for 30 minutes, and then an excessive amount of methanol was dropped to obtain a polyamide-imide powder. The powder was filtered under reduced pressure and dried, and then redissolved in DMAc to obtain a polymer resin solution with a solid content concentration of 14% by weight.

[0161] The obtained polymer resin solution was cast. A casting substrate was used for casting. There is no particular limitation on the type of casting substrate. As the casting substrate, a glass substrate, a stainless steel (SUS) substrate, a Teflon (registered trademark) substrate, etc. can be used. According to an embodiment of the present invention, an organic substrate can be used as the casting substrate.

[0162] Specifically, the obtained polymer resin solution was applied to a glass substrate, cast, dried with hot air at 80°C for 20 minutes and at 120°C for 20 minutes to produce a film. After that, the produced film was peeled off from the glass substrate and fixed to a frame with pins.

[0163] The frame with the film fixed was placed in an oven and dried with hot air at 270°C for 10 minutes under isothermal conditions. As a result, an optical film with a thickness of 50 μm was completed.

[0164] <Examples 2 to 14> In the same manner as in Example 1, the optical films of Examples 2 to 14 were produced, changing only the addition amount of the first diamine-based compound, the type and addition amount of the second diamine-based compound, the addition amount of the dianhydride-based compound, and the type and addition amount of the dicarbonyl-based compound.

[0165] The specific addition amounts of the first diamine-based compound, the type and addition amount of the second diamine-based compound, the addition amount of the dianhydride-based compound, and the type and addition amount of the dicarbonyl-based compound in Examples 1 to 14 are as shown in Table 1 below.

[0166] <Comparative Examples 1 to 3> In the same manner as in Example 1, the optical films of Comparative Examples 1 to 3 were produced by changing the addition amount of the first diamine-based compound, the presence or absence, type and addition amount of the second diamine-based compound, the addition amount of the dianhydride-based compound, and the addition amount of the dicarbonyl-based compound.

[0167] The specific addition amounts of the first diamine-based compound, the presence or absence, type and addition amount of the second diamine-based compound, the addition amount of the dianhydride-based compound, and the addition amount of the dicarbonyl-based compound in Comparative Examples 1 to 3 are as shown in Table 1 below.

[0168] <Comparative Example 4> While passing nitrogen through a 500 mL reactor equipped with a stirrer, a nitrogen injection device, a dropping funnel, a temperature regulator, and a cooler, after filling it with 313.34 g of DMAc (N,N-Dimethylacetamide), after adjusting the temperature of the reactor to 25 °C, 28.8207 g (0.090 mol) of TFDB was dissolved with a first diamine compound, and 2.483 g (0.010 mol) of 4DDS (Bis(4-aminophenyl)sulfone) was additionally dissolved with a second diamine compound, and this solution was maintained at 25 °C. After dissolving the diamine compounds, 5.8833 g (0.030 mol) of CBDA (Cyclobutane-1,2,3,4-tetracarboxylic dianhydride) and 2.2212 g (0.005 mol) of 6FDA were added thereto, and stirred for 2 hours to completely dissolve CBDA and 6FDA. After lowering the temperature of the reactor to 10 °C, 13.1989 g (0.065 mol) of TPC (Terephthaloyl Chloride) was added, completely dissolved and reacted in 1 hour, and then the temperature was raised to 25 °C. 0.35 g of pyridine and 0.45 g of acetic anhydride were introduced herein, stirred at 80 °C for 30 minutes, and then an excessive amount of methanol was dropped to obtain a polyamide-imide-based powder. After filtering the powder under reduced pressure and drying it, it was redissolved in DMAc to obtain a polymer resin solution having a solid content concentration of 14% by weight.

[0169] The obtained polymer resin solution was cast. A casting substrate was used for casting. There is no particular limitation on the type of the casting substrate. As the casting substrate, a glass substrate, a stainless steel (SUS) substrate, a Teflon (registered trademark) substrate, etc. can be used. According to an embodiment of the present invention, an organic substrate can be used as the casting substrate.

[0170] Specifically, the obtained polymer resin solution was applied to a glass substrate, cast, dried with hot air at 80 °C for 20 minutes and at 120 °C for 20 minutes to produce a film, and then the produced film was peeled off from the glass substrate and fixed to a frame with pins.

[0171] The frame with the film fixed was placed in an oven and dried with hot air at 270°C for 10 minutes isothermally. As a result, an optical film with a thickness of 50 μm was completed.

[0172] <Comparative Examples 5 and 6> In the same manner as in Example 1, the amounts of the first diamine compound, the second diamine compound, the dianhydride compound, and the dicarbonyl compound added were changed to produce the optical films of Comparative Examples 5 and 6.

[0173] The specific amounts of the first diamine compound, the second diamine compound, the dianhydride compound, and the dicarbonyl compound added in Comparative Examples 5 and 6 are as shown in Table 1 below.

[0174]

Table 1

[0175] TFDB: 2,2'-Bis(trifluoromethyl)benzidine 3DDS (2,2'-Bis(trifluoromethyl)benzidine) Bis(3-aminophenyl)sulfone (Bis(3-aminophenyl)sulfone) 4DDS: Bis(4-aminophenyl)sulfone (Bis(4-aminophenyl)sulfone) 3,3'-6F: 2,2-Bis(3-aminophenyl)hexafluoropropane (2,2-Bis(3-aminophenyl)hexafluoropropane) 4,4'-6F: 2,2-Bis(4-aminophenyl)hexafluoropropane (2,2-Bis(4-aminophenyl)hexafluoropropane) pPDA: para-Phenylene diamine (Para-phenylenediamine) 8FODA: Oxy-4,4'-bis(2,3,5,6-tetrafluoroaniline) (Oxy-4,4'-bis(2,3,5,6-tetrafluoroaniline)) TPC: Terephthaloyl Chloride (Terephthaloyl Chloride) BPDC: 4,4'-Biphenyl dicarbonyl Chloride (4,4'-Biphenyl dicarbonyl Chloride) CBDA: Cyclobutane-1,2,3,4-tetracarboxylic dianhydride (Cyclobutane-1,2,3,4-tetracarboxylic dianhydride)

[0176] <Measurement Example> For the polymer resins and films produced in Examples 1 to 14 and Comparative Examples 1 to 6, the following measurements were performed.

[0177] 1) Weight-average molecular weight of the polymer resin: Using GPC (Alliance e2695 / 2414 RID, Waters), the weight-average molecular weight of the polymer resin was measured under the following conditions.

[0178] Detector: 2414 RID, waters Mobile phase: 10 mM LiBr in DMAc Sample concentration: 0.25 (w / w)% in DMAc Column and detector temperature: 50 °C Flow Rate: 1.0 ml / min

[0179] 2) Modulus: Based on the standard specification ASTM D882, using a universal tensile testing machine (e.g., INSTRON), it was measured under the following conditions.

[0180] -25 °C / 50 RH% - Load Cell 30 KN, Grip 250 N. - Specimen size 10X50 mm, tensile speed 25 mm / min

[0181] 3) Poisson's ratio: The Poisson's ratio of the optical film was measured non - contact (Video extensometer) based on the standard specification ASTM E - 132. Specifically, it was measured using a universal material testing machine (for example, Instron 3367 of Instron Corporation) under the following conditions.

[0182] - Test speed: 10 mm / min -(25 ± 2)°C / (45 ± 5)%RH

[0183] 4) Elastic deformation index (E'): The elastic deformation index (E') of the optical film can be calculated by the following formula 2.

[0184] <Formula 2> Elastic deformation index (E') = E / (1 - v 2 )

[0185] 5) Yellowness index (Y.I.): The yellowness index was measured using a Spectrophotometer (CM - 3700D, KONICA MINOLTA) according to the standard specification ASTM E313.

[0186] 6) Folding performance parameter: The folding performance parameter of the optical film can be calculated by the following formula 1.

[0187] <Formula 1> JPEG0007714693000014.jpg1591

[0188] In the above formula 1, R is the radius of curvature of the optical film at the folding center line during folding, and the unit of the radius of curvature is mm, d is the thickness of the optical film, and the unit of the thickness is μm, and E' is the elastic deformation index. However, in the above formula 1, for the radius of curvature and the thickness, only numbers are substituted excluding the units.

[0189] 7) Light transmittance (%): Using a spectrophotometer (CM-3700D, KONICA MINOLTA), the average optical transmittance at wavelengths of 360 to 740 nm was measured.

[0190] 8) Haze: The manufactured optical film was cut into 50 mm Х 50 mm pieces, and haze was measured five times in accordance with ASTM D1003 using a haze meter from MURAKAMI (model name: HM-150), and the average value was taken as the haze value.

[0191] 9) Folding trace: A 100 mm Х 50 mm sample arbitrarily obtained from the optical film was subjected to a folding test around one folding axis. The folding test was carried out on a 100 mm Х 50 mm sample using a bending repetition evaluation machine (YUASA, DLDM111LHA) at 25°C / 50RH% with a curvature radius of 2.0 mm (diameter 4.0 mm) and a speed of 60 rpm, and repeated folding 200,000 times. After the folding test, the presence or absence of folding traces was analyzed around the folding axis.

[0192] At this time, an analysis method may be required to make the brightness (shadow), etc. of the folding trace (crease) clearer. As an example, as an imaging method, it can be carried out using a foreign matter inspection method for the film. As much as possible, various inspection methods such as reflective, scattering, and transmissive can be used to detect defects, indentations, and foreign matters of the same color as the material that are difficult to capture with a CCD camera or the naked eye, and it is preferably an inspection (i.e., determination) device rather than a measuring device.

[0193] As a specific example, it can be configured with three types: an inspection device + a control unit (controller box: converts laser data coming in through the inspection device into image data) + a dedicated PC (image PC: a PC with a dedicated application registered, capable of connecting to the control unit (controller box) and performing image processing). That is, after setting the measurement / evaluation conditions and converting them into an image file, analysis / evaluation can be carried out by utilizing a known program for analyzing the brightness, chroma, reflectivity, etc. of the image / photo, but it is not limited to this.

[0194] The measurement results are as shown in Table 2 and Table 3 below.

[0195]

Table 2

[0196]

Table 3

[0197] As disclosed in the measurement results of Table 2 and Table 3 above, it can be confirmed that Examples 1 to 14 of the present invention have a high weight average molecular weight, and all of the yellowness, light transmittance, and haze are excellent. In addition, in Examples 1 to 14 of the present invention, all of the folding performance parameters are 1.5 GPa or less, the elastic deformation index (E') is 5.5 GPa or more, and no folding trace occurred even after the folding test ("X" in Table 3).

[0198] However, in Comparative Example 1, due to the gelation of the dicarbonyl compound, it was impossible to manufacture it as a film. In Comparative Example 2, it was confirmed that the weight-average molecular weight of the resin was low, the yellowness and haze were high, and the visibility was low. Also, in Comparative Example 2, although the folding performance parameter was 1.5 GPa or less, the elastic deformation index (E') was less than 5.5 GPa, and after the folding test, some folding traces occurred ("△" in Table 3). In Comparative Example 3, although the weight-average molecular weight of the resin was large, the yellowness and haze were extremely high, and the light transmittance was extremely reduced. Also, in Comparative Example 3, although the folding performance parameter was 1.5 GPa or less, the elastic deformation index (E') was less than 5.5 GPa, and after the folding test, some folding traces occurred ("△" in Table 3). In Comparative Example 4, the yellowness and haze were high, the light transmittance was low, the folding performance parameter exceeded 1.5 GPa, and severe folding traces occurred after the folding test ("O" in Table 3). In Comparative Example 5, since the yellowness and haze were high and the light transmittance was low, it was confirmed that the visibility was low. Also, in Comparative Example 5, although the folding performance parameter was 1.5 GPa or less, the elastic deformation index (E') was less than 5.5 GPa, and some folding traces occurred after the folding test ("△" in Table 3). In Comparative Example 6, it was confirmed that the weight-average molecular weight of the resin was low, the yellowness and haze were high, and the light transmittance was low, so the visibility was low. Also, in Comparative Example 6, although the folding performance parameter was 1.5 GPa or less, the elastic deformation index (E') was less than 5.5 GPa, and after the folding test, some folding traces occurred ("△" in Table 3).

Explanation of Signs

[0199] 100: Optical film 200: Display device 501: Display panel

Claims

1. An optical film containing a polymer resin, wherein the polymer resin contains an imide repeating unit and an amide repeating unit, the imide repeating unit contains a first repeating unit and a second repeating unit, the amide repeating unit contains a third repeating unit and a fourth repeating unit, the first repeating unit is an imide repeating unit obtained by the polymerization reaction of a first diamine compound and a first dianhydride compound, the second repeating unit is an imide repeating unit obtained by the polymerization reaction of a second diamine compound and a second dianhydride compound, the third repeating unit is an amide repeating unit obtained by the polymerization reaction of a first diamine compound and a first dicarbonyl compound, the fourth repeating unit is an amide repeating unit obtained by the polymerization reaction of a second diamine compound and a second dicarbonyl compound, the first diamine compound is 2,2'-Bis(trifluoromethyl)benzidine (TFDB), the second diamine compound contains at least one of Bis(4-aminophenyl)sulfone (4DDS) and 2,2-Bis(3-aminophenyl)hexafluoropropane (3,3'-6F), the yellowing degree of the optical film is 3.0 or less, the folding performance parameter calculated by the following formula 1 is 1.5 GPa or less, Optical film: <Formula 1> In the formula 1, R is the radius of curvature of the optical film at the folding center line during folding and is 0.5 mm, d is the thickness of the optical film and the unit of thickness is μm, and E' is the elastic deformation index calculated by the following formula 2. However, in the formula 1, for the radius of curvature and the thickness, only numbers are substituted excluding the units. <Formula 2> Elastic deformation index (E') = E / (1 - v 2 ) In the formula 2, E is the modulus of the optical film and the unit of modulus is GPa, and v is the Poisson's ratio of the optical film.

2. The elastic deformation index (E') calculated by the formula 2 is 5.5 or more, The optical film according to claim 1.

3. The amide repeating unit is contained in a ratio of 80% or more with respect to the number of the imide repeating unit and the amide repeating unit. The optical film according to claim 1.

4. The molar ratio of the polymerized first diamine compound and the second diamine compound is 95:5 to 50:

50. The optical film according to claim 1.

5. The polymer resin has a weight-average molecular weight (Mw) of 200,000 to 500,000. The optical film according to claim 1.

6. A display panel; and The optical film according to any one of claims 1 to 5, disposed on the display panel; A display device including the same.

Images