Optical film with improved optical properties, display device including the same, and manufacturing method thereof

Abstract

The present invention provides an optical film containing a polymer resin, the polymer resin comprising a first repeating unit, a second repeating unit, a third repeating unit, and a fourth repeating unit, wherein the optical index of the film is 1.0% / GU or more, the first repeating unit is an imide repeating unit derived from a first diamine compound and a dianhydride compound, the second repeating unit is an imide repeating unit derived from a second diamine compound and a dianhydride compound, the third repeating unit is an amide repeating unit derived from a first diamine compound and a dicarbonyl compound, the fourth repeating unit is an amide repeating unit derived from a second diamine compound and a dicarbonyl compound, the first diamine compound is 2,2′-bis(trifluoromethyl)benzidine (TFDB), the second diamine compound includes an aromatic diamine compound, and the third repeating unit and the fourth repeating unit are included in a proportion of 80% or more relative to the total number of repeating units including the first to fourth repeating units.

Description

Technical Field

[0001] The present disclosure relates to an optical film having excellent optical properties, and more particularly, to an optical film having a high refractive index, a display device including the optical film, and a method of manufacturing the optical film. Background Art

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

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

[0004] Among optical films, polyimide (PI)-based resins have excellent insolubility, chemical resistance, heat resistance, radiation resistance, and low-temperature characteristics, and are used as automotive materials, aerospace materials, spacecraft materials, insulating coatings, insulating films, protective films, etc.

[0005] Recently, polyamide-imide-based resins in which amide repeating units are added to polyimide-based resins have been developed, and films prepared using the polyamide-imide-based resins have excellent optical properties as well as excellent insolubility, chemical resistance, heat resistance, radiation resistance, and low-temperature characteristics. Such polyamide-imide-based resins can be prepared using diamine compounds, dianhydride compounds, and dicarbonyl compounds as monomers.

[0006] However, for example, a problem caused by using 2,2'-bis(trifluoromethyl)benzidine (TFDB) as a diamine is that during the polymerization of TFDB with a large amount of dicarbonyl compounds, due to the rigid structure of TFDB, the dicarbonyl compounds gel, and thus the polymerization reaction is insufficient.

[0007] Therefore, it is necessary to develop a polyamide-imide-based resin that has a high degree of polymerization even when a large amount of dicarbonyl is added. Summary of the Invention

[0008] Technical Problem

[0009] One aspect of the present disclosure is to provide an optical film including a polymer resin that has a high degree of polymerization even when a large amount of dicarbonyl is added.

[0010] Another aspect of the present disclosure is to provide an optical film that exhibits excellent optical properties.

[0011] Another aspect of the present disclosure is to provide a method for manufacturing an optical film including a polymer resin having a high degree of polymerization.

[0012] Technical solution

[0013] According to the present disclosure, the above object and other objects can be achieved by providing an optical film including a polymer resin, the polymer resin including a first repeating unit, a second repeating unit, a third repeating unit, and a fourth repeating unit, and the optical index of the optical film calculated using the following Formula 1 being 1.0% / GU or more:

[0014] [Formula 1]

[0015]

[0016] wherein, the parallel transmittance of the film is obtained by measuring the parallel transmittance of a sample film having a size of 50 mm × 50 mm three times using a haze meter (model name: HM-150, MURAKAMI Corporation) and calculating the average value of the three measurement values, and the 20° glossiness and RSPEC of the film are measured by placing white paper under one side of a sample film having a size of 30 mm × 100 mm and measuring on the surface of the film using a glossiness meter (Rhopoint Instruments, RHOPOINT IQ), wherein, the first repeating unit is an imide repeating unit derived from a first diamine compound and a dianhydride compound, the second repeating unit is an imide repeating unit derived from a second diamine compound and the dianhydride compound, the third repeating unit is an amide repeating unit derived from the first diamine compound and a dicarbonyl compound, the fourth repeating unit is an amide repeating unit derived from the second diamine compound and the dicarbonyl compound, wherein, the first diamine compound is 2,2'-bis(trifluoromethyl)benzidine (TFDB), the second diamine compound includes an aromatic diamine compound, and the sum of the number of the third repeating unit and the fourth repeating unit is 80% or more of the total number of repeating units including the first to fourth repeating units.

[0017] The second diamine compound may include at least one selected from bis(3-aminophenyl)sulfone (3DDS), bis(4-aminophenyl)sulfone (4DDS), 2,2-bis(3-amino-4-methylphenyl)hexafluoropropane (AMH), 9,9-bis(4-aminophenyl)fluorene (FDA), 9,9-bis(3-fluoro-4-aminophenyl)fluorene (FFDA), m-phenylenediamine (mPDA), p-methylenedianiline (pMDA), m-methylenedianiline (mMDA), 1,3-bis(3-aminophenoxy)benzene (133APB), 1,3-bis(4-aminophenoxy)benzene (134APB), 1,4-bis(4-aminophenoxy)benzene (144APB), 2,2'-bis(3-aminophenyl)hexafluoropropane (33-6F), 2,2'-bis(4-aminophenyl)hexafluoropropane (44-6F), 2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane (6FAP), 2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane (HFBAPP), bis(4-(4-aminophenoxy)phenyl)sulfone (BAPS), bis(4-(3-aminophenoxy)phenyl)sulfone (BAPSM), 2,2-bis(4-(4-aminophenoxy)phenyl)propane (BAPP), 4,4-bis(4-aminophenoxy)biphenyl (BAPB), 3,3-diamino-4,4'-dihydroxydiphenylsulfone (DABS), 2,2'-bis(3-amino-4-hydroxyphenyl)propane (BAP), 4,4'-diaminodiphenyl ether (4-ODA), and 3,3'-diaminodiphenyl ether (3-ODA).

[0018] The ratio of the number of repeating units from the first diamine compound to the number of repeating units from the second diamine compound may be from 95:5 to 50:50.

[0019] Based on a thickness of 50 μm, the yellowness index (Y.I.) of the optical film may be 3.0 or less.

[0020] Based on a thickness of 50 μm, the light transmittance of the optical film may be 88.50% or more.

[0021] Based on a thickness of 50 μm, the 20° gloss of the optical film may be from 200 GU to 250 GU.

[0022] Based on a thickness of 50 μm, the RSPEC of the optical film may be from 140 GU to 190 GU.

[0023] According to another aspect of the present disclosure, there is provided a display device including: a display panel; and the optical film disposed on the display panel.

[0024] According to another aspect of the present disclosure, there is provided a method for manufacturing an optical film, the method comprising: forming a first reaction solution using a first diamine compound, a second diamine compound, a dianhydride compound, and a dicarbonyl compound, adding a dehydrating agent and an imidization catalyst to the first reaction solution and reacting them to form a second reaction solution, treating the second reaction solution to prepare a solid-phase polymer resin, dissolving the solid-phase polymer resin to prepare a polymer resin solution, and casting the polymer resin solution, wherein the first diamine compound is 2,2′-bis(trifluoromethyl)benzidine (TFDB), the second diamine compound includes an aromatic diamine compound, the packing density of the dicarbonyl compound is 0.5 g / ml to 0.8 g / ml, and the content of the dicarbonyl compound is more than 80 mole parts and the content of the dianhydride compound is less than 20 mole parts relative to the total content of 100 mole parts of the first diamine compound and the second diamine compound.

[0025] The method may further include: reducing the packing density of the dicarbonyl compound before forming the first reaction solution.

[0026] The second diamine compound may include at least one selected from bis(3-aminophenyl)sulfone (3DDS), bis(4-aminophenyl)sulfone (4DDS), 2,2-bis(3-amino-4-methylphenyl)hexafluoropropane (AMH), 9,9-bis(4-aminophenyl)fluorene (FDA), 9,9-bis(3-fluoro-4-aminophenyl)fluorene (FFDA), m-phenylenediamine (mPDA), p-methylenedianiline (pMDA), m-methylenedianiline (mMDA), 1,3-bis(3-aminophenoxy)benzene (133APB), 1,3-bis(4-aminophenoxy)benzene (134APB), 1,4-bis(4-aminophenoxy)benzene (144APB), 2,2′-bis(3-aminophenyl)hexafluoropropane (33-6F), 2,2′-bis(4-aminophenyl)hexafluoropropane (44-6F), 2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane (6FAP), 2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane (HFBAPP), bis(4-(4-aminophenoxy)phenyl)sulfone (BAPS), bis(4-(3-aminophenoxy)phenyl)sulfone (BAPSM), 2,2-bis(4-(4-aminophenoxy)phenyl)propane (BAPP), 4,4-bis(4-aminophenoxy)biphenyl (BAPB), 3,3-diamino-4,4,-dihydroxydiphenylsulfone (DABS), 2,2,-bis(3-amino-4-hydroxyphenyl)propane (BAP), 4,4′-diaminodiphenyl ether (4-ODA), and 3,3′-diaminodiphenyl ether (3-ODA).

[0027] Based on the total content of 100 parts by mole of the first diamine compound and the second diamine compound, the content of the first diamine compound can be 50 to 95 parts by mole, and the content of the second diamine compound can be 5 to 50 parts by mole.

[0028] Advantageous Effects

[0029] According to one embodiment of the present disclosure, by controlling the polymerization reaction of a diamine compound and a dicarbonyl compound, an optical film including a polymer resin having an excellent degree of polymerization can be provided even when a large amount of the dicarbonyl compound is added.

[0030] One embodiment of the present disclosure provides an optical film having excellent optical properties.

[0031] Another embodiment of the present disclosure provides a method for manufacturing an optical film, which can provide an optical film having a high degree of polymerization and excellent optical properties even when a large amount of the dicarbonyl compound is added.

[0032] The optical film according to another embodiment of the present disclosure exhibits excellent optical and mechanical properties. Therefore, 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

[0033] Figure 1 is a cross-sectional view showing a part of a display device according to one embodiment of the present disclosure;

[0034] Figure 2 is a cross-sectional view showing Figure 1 an enlarged view of the "P" part. DETAILED DESCRIPTION

[0035] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. However, the following embodiments are provided only for clearly understanding the present disclosure by way of example, and do not limit the scope of the present disclosure.

[0036] The shapes, sizes, ratios, angles, and numbers disclosed in the drawings for describing the embodiments of the present disclosure are only 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 the detailed description of related known functions or configurations is determined to unnecessarily obscure the gist of the present disclosure, the detailed description will be omitted.

[0037] In the case of using terms such as "comprising", "having", or "including" in this specification, unless "only" is used, there may also be other parts. Unless stated to the contrary, terms in the singular form may include plural meanings. In addition, when interpreting an element, even if there is no explicit description of it, the element is understood to include the error range.

[0038] When describing the positional relationship, for example, when the positional relationship is described as "on", "above", "under", or "next", unless "exactly" or "directly" is used, it may include the case where there is no contact between them.

[0039] Spatial relative terms such as "under", "below", "lower", "above", and "upper" may be used herein to describe the relationship between one device or element and another device or element as shown in the figures. It should be understood that, in addition to the directions depicted in the figures, the spatial relative terms are intended to include different directions of the device during the use or operation of the device. For example, if the device in one figure is inverted, the element described as "under" or "below" another element will be located "above" the other element. Therefore, the exemplary terms "under" or "below" may include both the meanings of "under" and "above". In the same way, the exemplary terms "above" or "upper" may include both the meanings of "above" and "under".

[0040] When describing the time relationship, for example, when using "after", "subsequently", "next", or "before" to describe the time sequence, unless "exactly" or "directly" is used, it may include the case of non - consecutive relationships.

[0041] It should be understood that although terms such as "first", "second", etc. may be used herein to describe different elements, these elements are not limited by these terms. These terms are only used to distinguish one element from another. Therefore, within the technical concept of the present disclosure, the first element may be referred to as the second element.

[0042] 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 all combinations of two or more elements selected from the first, second, and third elements, as well as each of the first, second, and third elements.

[0043] The features of the various embodiments of the present disclosure may be partially or completely combined or combined with each other, and may interact with each other in various ways and be technically driven. The embodiments of the present disclosure may be carried out independently of each other, or may be carried out together in a related manner.

[0044] One embodiment of the present disclosure provides an optical film. The optical film according to an embodiment of the present disclosure includes a polymer resin.

[0045] The polymer resin may be included in the film in any one of various shapes and forms, for example, as a solid powder, in a state dissolved in a solution, or as a matrix cured after being dissolved in a solvent. Any resin may be considered the same as the polymer resin of the present disclosure regardless of its shape and form as long as it is a resin containing the same repeating units as those in the present disclosure. Generally, the polymer resin may exist in the film in the form of a matrix, which is obtained by coating a polymer resin solution and drying it to form a solid.

[0046] The optical film according to an embodiment of the present disclosure may include at least one of an imide repeating unit and an amide repeating unit. For example, the optical film according to an embodiment of the present disclosure may include at least one of a polyimide-based polymer, a polyamide-based polymer, and a polyamide-imide-based polymer.

[0047] The optical film according to an embodiment of the present disclosure may include an imide repeating unit formed from a diamine compound and a dianhydride compound.

[0048] The optical film according to an embodiment of the present disclosure may include an amide repeating unit formed from a diamine compound and a dicarbonyl compound.

[0049] The optical film according to an embodiment of the present disclosure may include both an amide repeating unit and an imide repeating unit formed from a diamine compound, a dianhydride compound, and a dicarbonyl compound.

[0050] For example, the optical film according to an embodiment of the present disclosure may include at least one of a polyimide-based resin, a polyamide-based resin, and a polyamide-imide-based resin.

[0051] According to an embodiment of the present disclosure, the optical film may be any one of a polyimide-based film, a polyamide-based film, and a polyamide-imide-based film, but the embodiments of the present disclosure are not limited thereto. Any film having light transmissivity may be used as the optical film according to an embodiment of the present disclosure.

[0052] The polymer resin according to an embodiment of the present disclosure includes a first repeating unit, a second repeating unit, a third repeating unit, and a fourth repeating unit.

[0053] The first repeating unit is an imide repeating unit derived from a first diamine compound and a dianhydride compound, and the second repeating unit is an imide repeating unit derived from a second diamine compound and the dianhydride compound.

[0054] The third repeating unit is an amide repeating unit derived from the first diamine compound and the dicarbonyl compound, and the fourth repeating unit is an amide repeating unit derived from the second diamine compound and the dicarbonyl compound.

[0055] The sum of the number of amide repeating units including the third repeating unit and the fourth repeating unit is more than 80% of the total number of repeating units including the first to fourth repeating units.

[0056] As used herein, the term "repeating unit derived from..." means that a plurality of monomers used to form a polymer are connected to each other and arranged repeatedly in the polymer. This term is widely used in the field to which the present disclosure pertains. For example, polyethylene is a polymer having repeating units derived from ethylene, which has a structure in which a plurality of ethylene monomers are connected to each other and arranged repeatedly in the polyethylene polymer.

[0057] In the present disclosure, the imide repeating unit of the polymer resin can be prepared from monomer components including a diamine compound and a dianhydride compound. Specifically, the diamine compound and the dianhydride compound are polymerized to form an amic acid, and the amic acid is imidized to form an imide repeating unit. In addition, the amide repeating unit can also be prepared by the polymerization of monomer components including a diamine compound and a dicarbonyl compound. The specific structures of the imide repeating unit and the amide repeating unit can vary depending on the monomers used in the reaction.

[0058] However, the polymer resin according to an embodiment of the present disclosure is not limited thereto. The polymer resin according to an embodiment of the present disclosure can be prepared from monomer components further including other compounds in addition to the diamine compound, the dianhydride compound, and the dicarbonyl compound. Therefore, in addition to the imide repeating unit and the amide repeating unit, the polymer resin according to an embodiment of the present disclosure can also include other repeating units.

[0059] According to an embodiment of the present disclosure, the optical index of the optical film calculated using the following Formula 1 is 1.0% / GU or more:

[0060] [Formula 1]

[0061]

[0062] The optical index of the film of the present disclosure is obtained by dividing the parallel transmittance by the difference between the 20° glossiness and RSPEC.

[0063] The parallel transmittance of the film of the present disclosure can be obtained by measuring the parallel transmittance of a sample film with a size of 50 mm × 50 mm three times using a haze meter (model name: HM-150, MURAKAMICorporation) and calculating the average value of the three values. In addition, in the present disclosure, the 20° gloss and RSPEC of the film can be measured by placing a white paper under one side of a sample film with a size of 30 mm × 100 mm and measuring the surface of the film using a gloss meter (Rhopoint Instruments, RHOPOINT IQ).

[0064] In Formula 1, the parallel transmittance is a value obtained by subtracting the diffuse transmittance from the total transmittance of the film. In other words, the parallel transmittance is expressed as "total transmittance - diffuse transmittance".

[0065] In Formula 1, the 20° gloss is the gloss expressed based on the amount of light reflected from the surface of the film. Generally, the gloss of the film is measured at an angle of 60°. However, when the gloss is high (when the gloss measured at an angle of 60° is 70 GU or more), the gloss at an angle of 20° is measured. As used herein, the term "20° gloss" refers to the gloss of a high-gloss film measured at an angle of 20°.

[0066] In Formula 1, RSPEC represents the peak reflectance measured at a narrow angle (20° ± 0.09905°). RSPEC varies greatly depending on the texture of the surface. The RSPEC measured by the film can indicate the difference in texture, which is difficult to detect by a smooth surface. As the amount of foreign matter on the surface of the film increases, the value of RSPEC decreases. That is, if the RSPEC and the gloss value are the same, the surface of the film is considered to be smooth, and if there are more foreign matters (irregularities) on the surface, the RSPEC value decreases.

[0067] As the value of "20° gloss - RSPEC" decreases, the surface of the film becomes smoother.

[0068] The present inventors have found that the parallel transmittance and surface properties of the optical film affect the visibility of the optical film. Specifically, as the parallel transmittance of the optical film increases and the smoothness of the film surface increases, the optical performance is improved, and thus, the visibility is enhanced. As shown in Formula 1 above, the optical index of the film of the present disclosure is obtained by dividing the parallel transmittance by the difference between the 20° gloss and RSPEC. As the optical index of the film increases, the parallel transmittance increases, and as the surface of the film becomes smoother, the optical index of the optical film increases, and thus, the visibility is improved.

[0069] The optical index of the optical film of the present disclosure is 1.0% / GU or more. The optical index of the film is a parameter for evaluating the optical performance of the film. When the optical index of the optical film is less than 1.0% / GU, it is useless due to its low transparency.

[0070] According to one embodiment of the present disclosure, relative to the total content of 100 moles of the dianhydride compound and the dicarbonyl compound, the content of the dicarbonyl compound used in the production of the optical film is 80 moles or more, and relative to the total content of 100 moles of the dianhydride compound and the dicarbonyl compound, the content of the dianhydride compound is 20 moles or less. Preferably, the content of the dicarbonyl compound may be 95 moles or more, and the content of the dianhydride compound may be 5 moles or less. More preferably, the content of the dicarbonyl compound may be 98 moles or more, and the content of the dianhydride compound may be 2 moles or less.

[0071] Generally, since the diamine compound reacts with the dianhydride compound or the dicarbonyl compound in a ratio of about 1:1 during the preparation of the polymer resin, relative to 100 moles of the total content of the first diamine compound and the second diamine compound, the content of the dicarbonyl compound may be 80 moles or more, and the content of the dianhydride compound may be 20 moles or less.

[0072] In addition, since the first and second repeating units are from the dianhydride compound and the third and fourth repeating units are from the dicarbonyl compound, the sum of the number of amide repeating units including the third and fourth repeating units contained in the polymer resin can be said to correspond to 80% or more of the total number of repeating units including the first to fourth repeating units. Preferably, the sum of the number of the third and fourth repeating units can be said to correspond to 95% or more of the total number of repeating units including the first to fourth repeating units, and more preferably 98% or more.

[0073] When the sum of the number of amide repeating units including the third and fourth repeating units is 80% or more of the total number of repeating units including the first to fourth repeating units, the optical performance of the film can be maintained while its mechanical properties can be improved. That is, since the optical film contains more amide repeating units than imide repeating units, it is colorless and transparent, and has improved insolubility, chemical resistance, heat resistance, radiation resistance, low temperature characteristics, tensile strength, elongation, etc.

[0074] When a large amount of the dicarbonyl compound is added to form a large number of amide repeating units, the problem is that due to the gelation of the dicarbonyl compound, the polymerization reaction does not proceed sufficiently, and thus the degree of polymerization of the resin decreases. When the degree of polymerization of the resin decreases, the optical index of the film decreases, the visibility of the optical film decreases, and the quality of the optical film decreases.

[0075] In the present disclosure, gelling of dicarbonyl compounds can be prevented or inhibited by performing polymerization using two or more different types of diamine compounds. Accordingly, the polymer resin of the present disclosure includes repeating units from at least two types of diamine compounds including a first diamine compound and a second diamine compound.

[0076] Specifically, according to one embodiment of the present disclosure, the first diamine compound is 2,2'-bis(trifluoromethyl)benzidine (TFDB), and the second diamine compound includes aromatic diamine compounds other than TFDB. The imide repeating units and amide repeating units of the present disclosure can be derived from TFDB and aromatic diamine compounds other than TFDB.

[0077] Since 2,2'-bis(trifluoromethyl)benzidine (TFDB) as the first diamine compound has a specific linear and rigid structure, a film including repeating units from TFDB can be imparted with greatly improved mechanical properties such as insolubility, chemical resistance, heat resistance, radiation resistance, and low-temperature characteristics.

[0078] However, due to the rigid structure of TFDB, the polymerization between TFDB and dicarbonyl compounds is accelerated. This rapid polymerization causes only a part of the dicarbonyl compounds to react with the diamine compounds, and the remaining part of the dicarbonyl compounds can gel rather than polymerize. The gelling of the dicarbonyl compounds reduces the degree of polymerization of the resin and deteriorates the optical properties of the film. Accordingly, it is difficult to prepare a polymer resin including a large amount of amide repeating units only by adding TFDB. According to the present disclosure, the second diamine compound can prevent the gelling of the dicarbonyl compounds and improve the degree of polymerization of the polymer.

[0079] According to one embodiment of the present disclosure, the second diamine compound includes aromatic diamine compounds.

[0080] In one embodiment of the present disclosure, the term "aromatic diamine compound" refers to a diamine compound in which an amino group is directly bonded to an aromatic ring, and may include an aliphatic group or other substituents as part of its structure. The aromatic ring may be a monocyclic ring, a fused ring including a monocyclic ring directly connected thereto through a heteroatom, or a fused ring. Examples of the aromatic ring may include, but are not limited to, a benzene ring, a biphenyl ring, a naphthalene ring, an anthracene ring, and a fluorene ring.

[0081] According to one embodiment of the present disclosure, the second diamine compound may be represented by Chemical Formula 1 below:

[0082] [Chemical Formula 1]

[0083] H2N-A 1 -NH2

[0084] Among them, A 1 represents a divalent aromatic organic group. An aromatic organic group refers to an organic group in which π electrons are delocalized, whereby single bonds and double bonds are alternately connected to each other to form a ring. For example, A 1 may include a divalent aromatic organic group having 4 to 40 carbon atoms. The hydrogen atoms in the aromatic organic group in Chemical Formula 1 may be substituted with a halogen element, a hydrocarbon group, or a hydrocarbon group substituted with a halogen element. Here, the hydrocarbon group or the hydrocarbon group substituted with a halogen element may have 1 to 8 carbon atoms. For example, the hydrogen in A 1 may be substituted with -F, -CH3, -CF3, -OH, etc.

[0085] An optical film made of a diamine compound in which the hydrogen atoms are substituted with a hydrocarbon group substituted with fluorine can be imparted with excellent light transmittance and excellent processability.

[0086] A in Chemical Formula 1 1 may, for example, include a structure represented by any one of the following chemical formulas.

[0087]

[0088] In the above chemical formulas, * represents the bonding position. In the above chemical formulas, X may have a structure represented by the following chemical formula. Although there is no particular limitation on the bonding position of X on each ring, the bonding position of X may be, for example, the meta-position or the para-position on each ring.

[0089]

[0090] In the above chemical formulas, * represents the bonding position. In the above chemical formulas, W may independently be any one of a single bond, O, S, SO2, CO, CH2, C(CH3)2, and C(CF3)2. Although there is no particular limitation on the bonding position of W on each ring, the bonding position of W may be, for example, the meta-position or the para-position on each ring.

[0091] According to one embodiment of the present disclosure, the second diamine compound may include at least one selected from bis(3-aminophenyl)sulfone (3DDS), bis(4-aminophenyl)sulfone (4DDS), 2,2-bis(3-amino-4-methylphenyl)hexafluoropropane (AMH), 9,9-bis(4-aminophenyl)fluorene (FDA), 9,9-bis(3-fluoro-4-aminophenyl)fluorene (FFDA), m-phenylenediamine (mPDA), p-methylenedianiline (pMDA), m-methylenedianiline (mMDA), 1,3-bis(3-aminophenoxy)benzene (133APB), 1,3-bis(4-aminophenoxy)benzene (134APB), 1,4-bis(4-aminophenoxy)benzene (144APB), 2,2′-bis(3-aminophenyl)hexafluoropropane (33-6F), 2,2′-bis(4-aminophenyl)hexafluoropropane (44-6F), 2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane (6FAP), 2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane (HFBAPP), bis(4-(4-aminophenoxy)phenyl)sulfone (BAPS), bis(4-(3-aminophenoxy)phenyl)sulfone (BAPSM), 2,2-bis(4-(4-aminophenoxy)phenyl)propane (BAPP), 4,4-bis(4-aminophenoxy)biphenyl (BAPB), 3,3-diamino-4,4,-dihydroxydiphenylsulfone (DABS), 2,2,-bis(3-amino-4-hydroxyphenyl)propane (BAP), 4,4′-diaminodiphenyl ether (4-ODA), and 3,3′-diaminodiphenyl ether (3-ODA).

[0092] According to one embodiment of the present disclosure, the ratio of the number of repeating units from the first diamine compound to the number of repeating units from the second diamine compound (repeating units from the first diamine compound: repeating units from the second diamine compound) may be in the range of 95:5 to 50:50. Here, the term "repeating unit from the first diamine compound (or second diamine compound)" is intended to include both imide repeating units and amide repeating units from the first diamine compound (or second diamine compound).

[0093] Since the repeating units from the first diamine compound are the first and third repeating units, and the repeating units from the second diamine compound are the second and fourth repeating units, the sum of the number of the first and third repeating units corresponds to 50% to 95% of the total number of repeating units including the first to fourth repeating units. That is, based on the total content of 100 mole parts of the first diamine compound and the second diamine compound, the content of the first diamine compound for manufacturing the optical film can be 50 to 95 mole parts, and based on the total content of 100 mole parts of the first diamine compound and the second diamine compound, the content of the second diamine compound can be 5 to 50 mole parts.

[0094] Regarding "repeating units from the first diamine compound: repeating units from the second diamine compound", when the fraction of the repeating units from the first diamine compound increases to more than 95:5, the fraction of the repeating units from the TFDB and the dicarbonyl compound increases, and the haze increases. On the other hand, when the fraction of the repeating units from the second diamine compound increases to more than 50:50, the heat resistance and strength of the film decrease.

[0095] In one embodiment of the present disclosure, the dianhydride compound can be represented by the following Chemical Formula 2:

[0096] [Chemical Formula 2]

[0097]

[0098] wherein, A 2 represents a tetravalent organic group. For example, A 2 can include a tetravalent organic group having 4 to 40 carbon atoms. The hydrogen atoms in the organic group in Chemical Formula 2 can be substituted by a halogen element, a hydrocarbon group, or a hydrocarbon group substituted by a halogen element. Here, the hydrocarbon group or the hydrocarbon group substituted by a halogen element can have 1 to 8 carbon atoms.

[0099] A in Chemical Formula 2 2 can, for example, include a structure represented by any one of the following chemical formulas.

[0100]

[0101] In the above chemical formulas, * represents the bonding position. In the above chemical formulas, Z can independently be a single bond, O, S, SO2, CO, (CH2) n , (C(CH3)2) n and (C(CF3)2) nAny one of them, and n can be an integer from 1 to 5. Although there is no particular limitation on the bonding position of Z on each ring, the bonding position of Z can be, for example, the meta or para position on each ring.

[0102] In one embodiment of the present disclosure, the dianhydride compound may include one or more selected from 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), 3,3,4,4-biphenyltetracarboxylic dianhydride (BPDA), naphthalenetetracarboxylic dianhydride (NTDA), diphenylsulfone tetracarboxylic dianhydride (DSDA), 4,4'-oxybisphthalic anhydride (ODPA), bis(3,4-dicarboxyphenyl)dimethylsilane dianhydride (SIDA), 4,4-bis(3,4-dicarboxyphenoxy)-diphenyl sulfide dianhydride (BDSDA), diphenylsulfone tetracarboxylic dianhydride (SO2DPA), cyclobutane-1,2,3,4-tetracarboxylic dianhydride (CBDA), and 4,4'-(4,4'-isopropylidenediphenoxy)bis(phthalic anhydride) (BPADA).

[0103] The monomers used in the manufacture of the optical film according to one embodiment of the present disclosure may include, for example, various dianhydride compounds.

[0104] An optical film manufactured using a dianhydride compound in which a hydrogen atom is replaced by a hydrocarbon group substituted with fluorine can be imparted with excellent light transmittance and excellent processability.

[0105] According to one embodiment of the present disclosure, the dicarbonyl compound may be represented by the following Chemical Formula 3:

[0106] [Chemical Formula 3]

[0107]

[0108] Wherein, A 3 represents a divalent organic group. For example, A 3 may include a divalent organic group having 4 to 40 carbon atoms. The hydrogen atom in the organic group in Chemical Formula 3 may be replaced by a halogen element, a hydrocarbon group, or a hydrocarbon group substituted with fluorine. Here, the hydrocarbon group or the hydrocarbon group substituted with fluorine may have 1 to 8 carbon atoms. For example, the hydrogen in A 3 may be replaced by -F, -CH3, -CF3, etc.

[0109] A in Chemical Formula 3 3It may include, for example, a structure represented by any of the following chemical formulas.

[0110]

[0111] In the above chemical formulas, * represents the bonding position. In the above chemical formulas, Y can independently be any one of a single bond, O, S, SO2, CO, CH2, C(CH3)2, and C(CF3)2. Although there is no particular limitation on the bonding position of Y on each ring, the bonding position of Y can be, for example, the meta or para position on each ring.

[0112] According to one embodiment of the present disclosure, the dicarbonyl compound may include at least one selected from phthaloyl chloride, terephthaloyl chloride (TPC), isophthaloyl chloride (IPC), 4,4'-biphenyldicarbonyl chloride (DPDOC), 4,4'-oxybis(benzoyl chloride) (OBBOC), and naphthalene-2,3-dicarbonyl dichloride.

[0113] The polymer resin according to one embodiment of the present disclosure 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:

[0114] [Chemical Formula 4]

[0115]

[0116] wherein, A 2 As described above,

[0117] [Chemical Formula 5]

[0118]

[0119] wherein, A 1 and A 2 As described above.

[0120] The polymer resin according to one embodiment of the present disclosure 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:

[0121] [Chemical Formula 6]

[0122]

[0123] wherein, A 3 As described above,

[0124] [Chemical Formula 7]

[0125]

[0126] wherein, A1 and A 3 As described above.

[0127] According to an embodiment of the present disclosure, the optical film is light transmissive. In addition, the optical film is flexible. For example, the optical film according to an embodiment of the present disclosure is bendable, foldable, or rollable. The optical film may have excellent mechanical and optical properties.

[0128] According to an embodiment of the present disclosure, the optical film may have a thickness sufficient to protect the display panel. For example, the thickness of the optical film may be 10 μm to 100 μm.

[0129] Based on a thickness of 50 μm, the yellowness index of the optical film according to an embodiment of the present disclosure may be 3.0 or less. In addition, based on a thickness of 50 μm, the yellowness index of the optical film according to an embodiment of the present disclosure may be 2.0 or less, or the yellowness index may be 1.0 or less.

[0130] Based on a thickness of 50 μm, the light transmittance of the optical film according to an embodiment of the present disclosure measured using a UV spectrophotometer in the visible light region may be 88.50% or more. In addition, based on a thickness of 50 μm, the light transmittance of the optical film according to an embodiment of the present disclosure may be 90% or more, or the light transmittance may be 91% or more.

[0131] According to the ASTM E313 standard, the yellowness index and the light transmittance can be measured using a spectrophotometer in the wavelength range of 360 nm to 740 nm. The spectrophotometer used here may be, for example, CM-3700D manufactured by KONICA MINOLTA.

[0132] Based on a thickness of 50 μm, the parallel transmittance of the optical film according to an embodiment of the present disclosure may be 87.50%.

[0133] As described above, the parallel transmittance is a value obtained by subtracting the diffuse transmittance of the film from the total transmittance of the film. In other words, the parallel transmittance is expressed as "total transmittance - diffuse transmittance". That is, the parallel transmittance of the film can be obtained by measuring the parallel transmittance of a sample film having a size of 50 mm × 50 mm three times using a haze meter (model name: HM-150, MURAKAMI Corporation) and calculating the average of the three measured values.

[0134] Based on a thickness of 50 μm, the 20° gloss of the optical film according to an embodiment of the present disclosure may be 200 GU to 250 GU.

[0135] The 20° gloss is a characteristic of gloss, which is expressed based on the amount of light reflected from the surface of the film. Generally, the gloss of the film is measured at an angle of 60°. However, when the gloss is high (when the gloss measured at an angle of 60° is 70 GU or more), the gloss at an angle of 20° is measured. As used herein, the term "20° gloss" refers to the gloss of a high-gloss film measured at an angle of 20°.

[0136] Based on a thickness of 50 μm, the RSPEC of the optical film according to one embodiment of the present disclosure can be 140 GU to 190 GU.

[0137] RSPEC represents the peak reflectance measured at a narrow angle (20° ± 0.09905°). RSPEC varies greatly depending on the surface texture. The RSPEC of the measured film can indicate differences in texture, which are difficult to detect by a smooth surface. As the amount of foreign matter on the surface of the film increases, the RSPEC value decreases. That is, if the RSPEC and the gloss value are the same, the surface of the film is considered smooth, and if there are more foreign matters (irregularities) on the surface, the RSPEC value decreases.

[0138] The 20° gloss and RSPEC can be measured by placing a white paper under one side of a sample film having a size of 30 mm × 100 mm and using a gloss meter (Rhopoint Instruments, RHOPOINT IQ) to measure the 20° gloss and RSPEC of the surface of the sample film.

[0139] Hereinafter, reference will be made to Figure 1 and Figure 2 to describe a display device including an optical film according to one embodiment of the present disclosure.

[0140] Figure 1 is a cross-sectional view showing a part of a display device 200 according to another embodiment, Figure 2 is Figure 1 an enlarged cross-sectional view of the "P" part in

[0141] Referring to Figure 1 According to another embodiment of the present disclosure, the display device 200 includes: a display panel 501; and an optical film 100 on the display panel 501.

[0142] Referring to Figure 1 and Figure 2, the display panel 501 includes: a substrate 510; thin film transistors TFTs on the substrate 510; and an organic light emitting device 570 connected to the thin film transistors TFTs. 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 1 and Figure 2 The display device 200 shown in

[0143] The substrate 510 may be formed of glass or plastic. Specifically, the substrate 510 may be formed of plastic such as a polymer resin or an optical film. Although not shown, a buffer layer may be provided on the substrate 510.

[0144] The thin film transistors TFTs are provided on the substrate 510. The thin film transistors TFTs 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.

[0145] Referring to Figure 2 , 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.

[0146] A planarization layer 552 is provided on the thin film transistors TFTs to planarize the tops of the thin film transistors TFTs.

[0147] The first electrode 571 is provided on the planarization layer 552. The first electrode 571 is connected to the thin film transistors TFTs through contact holes provided in the planarization layer 552.

[0148] A bank layer 580 is provided 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 provided in a matrix form at the boundaries between a plurality of pixels to define respective pixel regions.

[0149] The organic light emitting layer 572 is provided on the first electrode 571. The organic light emitting layer 572 may also be provided on the bank layer 580. The organic light emitting layer 572 may include one light emitting layer, or two light emitting layers stacked in the vertical direction. Light of any one of red, green, and blue colors may be emitted by the organic light emitting layer 572, and white light may be emitted by it.

[0150] The second electrode 573 is provided on the organic light emitting layer 572.

[0151] 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.

[0152] Although not shown, when the organic light-emitting layer 572 emits white light, each pixel may include a color filter for filtering the white light emitted from the organic light-emitting layer 572 based on a specific wavelength. The color filter is formed in the optical path.

[0153] The thin-film encapsulation layer 590 may be provided 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 provided.

[0154] The optical film 100 is provided on the display panel 501 having the above-described stacked structure.

[0155] Hereinafter, a method for manufacturing an optical film according to another embodiment of the present disclosure will be described.

[0156] A method for manufacturing an optical film according to an embodiment of the present disclosure includes: forming a first reaction solution using a first diamine compound, a second diamine compound, a dianhydride compound, and a dicarbonyl compound, adding a dehydrating agent and an imidization catalyst to the first reaction solution, and reacting them to form a second reaction solution, treating the second reaction solution to prepare a solid-phase polymer resin, dissolving the solid-phase polymer resin to prepare a polymer resin solution, and casting the polymer resin solution. Hereinafter, each step will be described in detail.

[0157] First, a first reaction solution is formed using a first diamine compound, a second diamine compound, a dianhydride compound, and a dicarbonyl compound.

[0158] The formation of the first reaction solution may be carried out by polymerizing the monomers used to form the polymer resin. The polymer resin may be prepared from monomer components including a first diamine compound, a second diamine compound, a dianhydride compound, and a dicarbonyl compound. In the present disclosure, there is no limitation on the addition order or addition method of the monomers. For example, the dianhydride compound and the dicarbonyl compound may be added to a solution in which the diamine compound is dissolved, and the resulting mixture may be polymerized.

[0159] The solvent used to prepare the first reaction solution may 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 solvent according to an embodiment of the present disclosure is not limited thereto, and other solvents may be used.

[0160] 2,2'-Bis(trifluoromethyl)benzidine (TFDB) can be used as the first diamine compound, the aromatic diamine compound of Chemical Formula 1 above can be used as the second diamine compound, the compound of Chemical Formula 2 above can be used as the dianhydride compound, and the compound represented by Chemical Formula 3 above can be used as the dicarbonyl compound.

[0161] For example, the second diamine compound may be bis(3-aminophenyl)sulfone (3DDS), bis(4-aminophenyl)sulfone (4DDS), 2,2-bis(3-amino-4-methylphenyl)hexafluoropropane (AMH), 9,9-bis(4-aminophenyl)fluorene (FDA), 9,9-bis(3-fluoro-4-aminophenyl)fluorene (FFDA), m-phenylenediamine (mPDA), p-methylenedianiline (pMDA), m-methylenedianiline (mMDA), 1,3-bis(3-aminophenoxy)benzene (133APB), 1,3-bis(4-aminophenoxy)benzene (134APB), 1,4-bis(4-aminophenoxy)benzene (144APB), 2,2'-bis(3-aminophenyl)hexafluoropropane (33-6F), 2,2'-bis(4-aminophenyl)hexafluoropropane (44-6F), 2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane (6FAP), 2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane (HFBAPP), bis(4-(4-aminophenoxy)phenyl)sulfone (BAPS), bis(4-(3-aminophenoxy)phenyl)sulfone (BAPSM), 2,2-bis(4-(4-aminophenoxy)phenyl)propane (BAPP), 4,4-bis(4-aminophenoxy)biphenyl (BAPB), 3,3-diamino-4,4-dihydroxydiphenylsulfone (DABS), 2,2,-bis(3-amino-4-hydroxyphenyl)propane (BAP), 4,4'-diaminodiphenyl ether (4-ODA), 3,3'-diaminodiphenyl ether (3-ODA), etc.

[0162] The dianhydride compounds may be 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), 3,3,4,4-biphenyltetracarboxylic dianhydride (BPDA), naphthalenetetracarboxylic dianhydride (NTDA), diphenylsulfone tetracarboxylic dianhydride (DSDA), 4,4'-oxybisphthalic anhydride (ODPA), bis(3,4-dicarboxyphenyl)dimethylsilane dianhydride (SIDA), 4,4-bis(3,4-dicarboxyphenoxy)-diphenyl sulfide dianhydride (BDSDA), diphenylsulfone tetracarboxylic dianhydride (SO2DPA), cyclobutane-1,2,3,4-tetracarboxylic dianhydride (CBDA), 4,4'-(4,4'-isopropylidenediphenoxy)bis(phthalic anhydride) (6HBDA), etc.

[0163] The dicarbonyl compounds may be phthaloyl chloride, terephthaloyl chloride (TPC), isophthaloyl chloride (IPC), 4,4'-biphenyldicarbonyl chloride (DPDOC), 4,4'-oxybis(benzoyl chloride) (OBBOC), naphthalene-2,3-dicarbonyl dichloride, etc.

[0164] The first diamine compounds, the second diamine compounds, the dianhydride compounds, and the dicarbonyl compounds may be used alone or in combination of two or more of them.

[0165] According to one embodiment of the present disclosure, based on the total content of 100 parts by mole of the first diamine compounds and the second diamine compounds, the amount of the dicarbonyl compounds may be 80 parts by mole or more, and the amount of the dianhydride compounds may be 20 parts by mole or less. Preferably, based on the total content of 100 parts by mole of the first diamine compounds and the second diamine compounds, the amount of the dicarbonyl compounds may be 95 parts by mole or more, and more preferably, 98 parts by mole or more.

[0166] The influence effect of the addition amount of the dicarbonyl compounds is as described above.

[0167] According to one embodiment of the present disclosure, based on the total content of 100 parts by mole of the first diamine compounds and the second diamine compounds, the amount of the first diamine compounds may be 50 parts by mole to 95 parts by mole.

[0168] The influence effect of the addition amount of the first diamine compounds is as described above.

[0169] According to another embodiment of the present disclosure, the bulk density of the dicarbonyl compound added to form the first reaction solution is from 0.5 g / ml to 0.8 g / ml.

[0170] Due to the linear and rigid structure of 2,2′-bis(trifluoromethyl)benzidine (TFDB) as the first diamine compound, it rapidly polymerizes with the dicarbonyl compound. Due to the nature of the preparation process of the dicarbonyl compound, the dicarbonyl compound is added in the form of flakes. The reaction of the dicarbonyl flake material with the diamine proceeds rapidly around its outer periphery, and the dicarbonyl compound present therein gels rather than participates in the polymerization. The gelling hinders the control of the degree of polymerization of the resin, and the gelled material reduces the transparency of the film.

[0171] According to another embodiment of the present disclosure, when using a dicarbonyl compound having a bulk density of from 0.5 g / ml to 0.8 g / ml, gelling of the dicarbonyl compound can be prevented or inhibited.

[0172] The bulk density of the dicarbonyl compound can be determined by using the apparent bulk density and calculating the average of three measurement values according to the ASTM D1895 standard.

[0173] When the bulk density of the dicarbonyl compound is less than 0.5 g / ml, the raw material is blown off and difficult to handle during processing. On the other hand, when the bulk density is greater than 0.8 g / ml, the gelling of the dicarbonyl compound becomes severe, and the optical properties and refractive index of the film are reduced.

[0174] According to another embodiment of the present disclosure, the first reaction solution contains polyamic acid and polyamide repeating units. Polyamic acid is a precursor of polyimide.

[0175] According to another embodiment of the present disclosure, the method for manufacturing an optical film may further include: before forming the first reaction solution, reducing the bulk density of the dicarbonyl compound.

[0176] The dicarbonyl compound is obtained in the form of a liquid dicarbonyl compound by vacuum distillation in the manufacturing process and crystallizes into a massive solid. Therefore, due to the nature of the manufacturing process, the dicarbonyl compound is used in the form of flakes. Generally, the bulk density of the dicarbonyl compound present in the form of flakes is about 8.8 g / ml, which is higher than 0.8 g / ml. When adding a dicarbonyl compound having a bulk density higher than 0.8 g / ml, the dicarbonyl compound gels.

[0177] The method further includes: before adding the dicarbonyl compound to the solution, reducing the bulk density of the dicarbonyl compound, thereby preventing or inhibiting gelling.

[0178] In the step of reducing the bulk density, for example, a mixer can be used to pulverize the dicarbonyl compound. Pulverizing the dicarbonyl compound using a mixer can adjust the bulk density of the dicarbonyl compound to 0.8 g / ml or less. By using a dicarbonyl compound having a bulk density of 0.8 g / ml or less, gelation can be prevented or inhibited.

[0179] Next, a dehydrating agent and an imidization catalyst are added to the first reaction solution and allowed to react therebetween to form a second reaction solution.

[0180] During the formation of the second reaction solution, a part of the amic acid is imidized to form an imide repeating unit.

[0181] According to an embodiment of the present disclosure, a dehydrating agent and an imidization catalyst are added to the first reaction solution, and then refluxed at a temperature of 60°C to 80°C for 30 minutes to 2 hours. As a result, a second reaction solution can be formed.

[0182] 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.

[0183] As the imidization catalyst, a tertiary amine such as isoquinoline, β-picoline or pyridine can be used.

[0184] Next, the second reaction solution is processed to prepare a solid-phase polymer resin.

[0185] To prepare a solid-phase polymer resin, a solvent can be added to the second reaction solution. The solvent can be, for example, ethanol, methanol, hexane, etc. The solvent can be used alone or as a mixture of two or more solvents.

[0186] When a solvent having low polarity and miscible with the polymerization solvent is added to the second reaction solution, a powdery solid polymer resin precipitates. By filtering and drying the precipitate, a high-purity solid polymer resin can be obtained. When removing the liquid component during the filtration of the precipitate, unreacted monomers, oligomers, additives and reaction by-products are removed. The polymer resin can be a polyamide-imide resin containing an imide repeating unit and an amide repeating unit.

[0187] Next, the solid-phase polymer resin is dissolved to prepare a polymer resin solution. By dissolving the solid-phase polymer resin in a solvent, a polymer resin solution can be prepared. This step is also referred to as "re-dissolution".

[0188] The solvent for dissolving the solid-phase polymer resin may be the same as any solvent used in the polymerization. Solvents that can be used to dissolve the solid-phase polymer resin may be, for example, polar aprotic organic solvents 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 mixtures thereof. However, the solvents according to the present disclosure are not limited thereto, and other well-known solvents may also be used.

[0189] Next, the polymer resin solution is cast.

[0190] Casting is performed using a casting substrate. There is 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, or the like. According to one embodiment of the present disclosure, the casting substrate may be, for example, a glass substrate.

[0191] Specifically, casting is achieved by coating the polymer resin solution onto the casting substrate. A coater, a doctor blade, or the like may be used for casting.

[0192] After casting, the polymer resin solution is dried while raising the temperature at a rate of 2 °C / min to 80 °C to 120 °C to produce a coating film of the polymer resin. The coating film produced in this manner can be said to be an intermediate of the optical film. After the coating film is tensioned and fixed to a pin-type tenter, heat treatment is performed while raising the temperature from 120 °C to 250 °C to 350 °C at a heating rate of 3 °C / min. When the temperature reaches the maximum coating film formation temperature, additional heat treatment may be performed in a constant temperature atmosphere for 10 minutes to 30 minutes. As a result, an optical film can be produced.

[0193] Hereinafter, the present disclosure will be described in more detail with reference to exemplary embodiments and comparative examples. However, the following embodiments and comparative examples should not be construed as limiting the scope of the present disclosure.

[0194] <Example 1>

[0195] 397.27 g of N,N-dimethylacetamide (DMAc) was added to a 500 mL reactor equipped with a stirrer, a nitrogen injector, a dropping funnel, a temperature controller, and a cooler, while passing nitrogen through the reactor. Then, the temperature of the reactor was adjusted to 25 °C, 28.82 g (0.09 mol) of TFDB as the first diamine compound was dissolved therein, 3.84 g (0.01 mol) of FFDA as the second diamine compound was further dissolved therein, and the resulting solution was maintained at 25 °C. 2.22 g (0.005 mol) of 6FDA was added to the resulting diamine solution and completely dissolved therein by stirring for 2 hours. The reactor temperature was lowered to 10 °C, and 19.29 g (0.095 mol, bulk density of 0.67 g / ml) of terephthaloyl chloride (TPC) was added thereto, completely dissolved, and reacted for 1 hour, and then the temperature was raised to 25 °C (the first reaction solution). The TPC added to the solution was the raw material crushed by a mixer.

[0196] The bulk density of the crushed TPC was determined by calculating the average value of three measurements according to the ASTM D1895 standard using the apparent bulk density. The bulk density was 0.67 g / ml.

[0197] 0.87 g of pyridine and 1.12 g of acetic anhydride were added to the first reaction solution, stirred for 30 minutes and heated to prepare a polymer resin solution with a solid concentration of 12 wt% (the second reaction solution).

[0198] The resulting 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 substrate, etc. can be used. According to an embodiment of the present disclosure, an organic substrate can be used as the casting substrate.

[0199] Specifically, the resulting polymer resin solution was coated on a glass substrate, cast, dried with hot air at 80 °C for 20 minutes, and dried at 120 °C for 20 minutes to manufacture a film. Then, the manufactured film was peeled off from the glass substrate and fixed to a frame with pins.

[0200] The frame with the film fixed thereon was placed in an oven, and then dried with hot air at a constant temperature of 290 °C for 30 minutes. As a result, an optical film with a thickness of 50 μm was completed. <>

[0201] <Example 2>

[0202] The optical film of Example 2 was manufactured in the same manner as in Example 1, except that the addition amount of the first diamine (TFDB), the type and amount of the second diamine, the addition amount of the dianhydride compound (6FDA), and the addition amount of the dicarbonyl compound (TPC) were changed.

[0203] <Examples 3 and 4>

[0204] A polymer resin solution (second reaction solution) was prepared in the same manner as in Example 1, except that the addition amount of the first diamine (TFDB), the type and amount of the second diamine, the addition amount of the dianhydride compound (6FDA), and the addition amount of the dicarbonyl compound (TPC) were changed.

[0205] The obtained polymer resin solution was cast to form a film. Then, the formed film was fixed to a frame with pins, and the frame with the film was placed in an oven and dried with hot air at a constant temperature of 260 °C for 10 minutes. As a result, the optical films of Examples 3 and 4 were manufactured.

[0206] <Example 5>

[0207] The optical film of Example 5 was manufactured in the same manner as in Example 1, except that the addition amount of the first diamine (TFDB), the type and amount of the second diamine, the addition amount of the dianhydride compound (6FDA), and the addition amount of the dicarbonyl compound (TPC) were changed.

[0208] <Example 6>

[0209] A polymer resin solution (second reaction solution) was prepared in the same manner as in Example 1, except that the addition amount of the first diamine (TFDB), the type and amount of the second diamine, the addition amount of the dianhydride compound (6FDA), and the addition amount of the dicarbonyl compound (TPC) were changed. In the same manner as in Example 1, the obtained polymer resin solution was cast and dried with hot air at 80 °C for 20 minutes and then at 120 °C for 20 minutes to form a film. Then, the formed film was peeled off from the glass substrate and fixed to a frame with pins.

[0210] The frame with the film was placed in an oven and dried with hot air at a constant temperature of 270 °C for 10 minutes. As a result, an optical film with a thickness of 50 μm of Example 6 was manufactured.

[0211] Details of the addition amount of the first diamine (TFDB), the type and amount of the second diamine, the addition amount of the dianhydride compound (6FDA), and the addition amount of the dicarbonyl compound (TPC) in Examples 1 to 6 are shown in Table 1 below.

[0212] <Comparative Examples 1 to 2>

[0213] Except for changing the addition amount of the first diamine (TFDB), the type and addition amount of the second diamine, the addition amount of the dianhydride compound (6FDA), the addition amount of the dicarbonyl compound (TPC), and the bulk density of the dicarbonyl compound (TPC), the optical films of Comparative Example 1 and Comparative Example 2 were produced in the same manner as in Example 1.

[0214] <Comparative Example 3>

[0215] Except for changing the addition amount of the first diamine (TFDB), the type and amount of the second diamine, the addition amount of the dianhydride compound (6FDA), the addition amount of the dicarbonyl compound (TPC), and the bulk density of the dicarbonyl compound (TPC), the polymer resin solution (second reaction solution) was prepared in the same manner as in Example 1.

[0216] The obtained polymer resin solution was cast to produce a film. Then, the produced film was fixed to a frame with pins, the frame with the film fixed thereon was placed in an oven, and then dried with hot air at a constant temperature of 260 °C for 10 minutes. As a result, the optical film of Comparative Example 3 was produced.

[0217] <Comparative Example 4>

[0218] Except for changing the addition amount of the first diamine (TFDB), the type and addition amount of the second diamine, the addition amount of the dianhydride compound (6FDA), the addition amount of the dicarbonyl compound (TPC), and the bulk density of the dicarbonyl compound (TPC), the optical film of Comparative Example 4 was produced in the same manner as in Example 1.

[0219] <Comparative Example 5>

[0220] Except for changing the addition amount of the first diamine (TFDB), the type and amount of the second diamine, the addition amount of the dianhydride compound (6FDA), the addition amount of the dicarbonyl compound (TPC), and the bulk density of the dicarbonyl compound (TPC), the polymer resin solution (second reaction solution) was prepared in the same manner as in Example 1. In the same manner as in Example 1, the obtained polymer resin solution was cast and dried with hot air at 80 °C for 20 minutes and then at 120 °C for 20 minutes to produce a film. Then, the produced film was peeled off from the glass substrate and fixed to a frame with pins.

[0221] The frame with the film fixed thereon was placed in an oven, and then dried with hot air at a constant temperature of 270 °C for 10 minutes. As a result, an optical film with a thickness of 50 μm of Comparative Example 5 was produced.

[0222] Details of the addition amounts of the first and second diamines (TFDB), the types and amounts of the second diamines, the addition amount of the dianhydride compound (6FDA), the addition amount of the dicarbonyl compound (TPC), and the bulk density of the dicarbonyl compound (TPC) in Comparative Examples 1 to 5 are shown in Table 1 below.

[0223] [Table 1]

[0224]

[0225] FFDA: 9,9-bis(3-fluoro-4-aminophenyl)fluorene

[0226] AMH: 2,2-bis(3-amino-4-methylphenyl)hexafluoropropane

[0227] 3DDS: bis(3-aminophenyl)sulfone

[0228] 4DDS: bis(4-aminophenyl)sulfone

[0229] <Measurement Example>

[0230] The following measurements were made on the polymer resins and films produced in Examples 1 to 6 and Comparative Examples 1 to 5.

[0231] 1) Yellowness index (Y.I.): The yellowness index was measured using a spectrophotometer (CM-3700D, KONICA MINOLTA) according to ASTM E313 standard.

[0232] 2) Transmittance (%): The average transmittance at wavelengths from 360 nm to 740 nm was measured using a spectrophotometer (CM-3700D, KONICA MINOLTA).

[0233] 3) Parallel transmittance (%): The parallel transmittance is expressed as "total transmittance - diffuse transmittance". The parallel transmittance of the film was obtained by measuring the parallel transmittance of a sample film with a size of 50 mm × 50 mm three times using a haze meter (model name: HM-150, MURAKAMI Corporation) and calculating the average of the three measured values.

[0234] 4) 20° glossiness (GU) and RSPEC (GU): The 20° glossiness (GU) and RSPEC (GU) were measured by placing a white paper under one side of a sample film with a size of 30 mm × 100 mm and measuring on the surface of the film using a gloss meter (Rhopoint Instruments, RHOPOINT IQ).

[0235] 5) Optical index of the film (% / GU): Using the measured parallel transmittance, 20° gloss, and RSPEC of the film, calculate the optical index of the film according to Equation 1 below.

[0236] [Equation 1]

[0237]

[0238] The measurement results are shown in Table 2 below.

[0239] [Table 2]

[0240]

[0241]

[0242] It can be seen from the measurement results in Table 2 that the films of Examples 1 to 6 of the present disclosure exhibit excellent yellowness index and light transmittance, and have a high optical index of more than 1.0% / GU. In other words, they have excellent optical properties.

[0243] However, in Comparative Example 4, polymerization could not occur due to gelation, and thus, a film could not be manufactured. In Comparative Examples 1, 2, and 5, the yellowness index exceeded 3.0. In Comparative Example 5, the light transmittance was less than 88.50%, and thus, the visibility was poor compared to the films of Examples 1 to 6. In addition, in Comparative Examples 1 to 3 and 5, the optical index of the film was less than 1.0% / GU.

[0244] [Description of reference numerals]

[0245] 100: Optical film

[0246] 200: Display device

[0247] 501: Display panel

Claims

1. An optical film comprising a polymer resin containing a first repeating unit, a second repeating unit, a third repeating unit, and a fourth repeating unit, The optical index of the optical film calculated using the following Formula 1 is 1.0% / GU or more: [Formula 1] Among them, The parallel transmittance of the optical film is obtained by measuring the parallel transmittance of a sample film having a size of 50 mm × 50 mm three times using a haze meter and calculating the average value of the three measurement values, and The glossiness and RSPEC of the optical film are measured by placing a white paper under one side of a sample film sized 30 mm × 100 mm and performing measurements on the surface of the optical film using a glossmeter, for the 20 o glossiness and RSPEC, wherein the first repeating unit is an imide repeating unit derived from a first diamine compound and a dianhydride compound, the second repeating unit is an imide repeating unit derived from a second diamine compound and the dianhydride compound, the third repeating unit is an amide repeating unit derived from the first diamine compound and a dicarbonyl compound, the fourth repeating unit is an amide repeating unit derived from the second diamine compound and the dicarbonyl compound, wherein the first diamine compound is 2,2'-bis(trifluoromethyl)benzidine (TFDB), and the second diamine compound includes an aromatic diamine compound, wherein the ratio of the number of repeating units derived from the first diamine compound to the number of repeating units derived from the second diamine compound is from 95:5 to 50:50, wherein the packing density of the dicarbonyl compound is from 0.5 g / ml to 0.8 g / ml, and the sum of the number of the third repeating unit and the fourth repeating unit is 80% or more of the total number of repeating units including the first to fourth repeating units.

2. The optical film according to claim 1, wherein, The second diamine compound includes at least one selected from bis(3-aminophenyl)sulfone (3DDS), bis(4-aminophenyl)sulfone (4DDS), 2,2-bis(3-amino-4-methylphenyl)hexafluoropropane (AMH), 9,9-bis(4-aminophenyl)fluorene (FDA), 9,9-bis(3-fluoro-4-aminophenyl)fluorene (FFDA), m-phenylenediamine (mPDA), p-methylenedianiline (pMDA), m-methylenedianiline (mMDA), 1,3-bis(3-aminophenoxy)benzene (133APB), 1,3-bis(4-aminophenoxy)benzene (134APB), 1,4-bis(4-aminophenoxy)benzene (144APB), 2,2'-bis(3-aminophenyl)hexafluoropropane (33-6F), 2,2'-bis(4-aminophenyl)hexafluoropropane (44-6F), 2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane (6FAP), 2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane (HFBAPP), bis(4-(4-aminophenoxy)phenyl)sulfone (BAPS), bis(4-(3-aminophenoxy)phenyl)sulfone (BAPSM), 2,2-bis(4-(4-aminophenoxy)phenyl)propane (BAPP), 4,4-bis(4-aminophenoxy)biphenyl (BAPB), 3,3-diamino-4,4,-dihydroxydiphenylsulfone (DABS), 2,2,-bis(3-amino-4-hydroxyphenyl)propane (BAP), 4,4'-diaminodiphenyl ether (4-ODA), and 3,3'-diaminodiphenyl ether (3-ODA).

3. The optical film according to claim 1, wherein, Based on a thickness of 50 μm, the yellowness index (Y.I.) of the optical film is 3.0 or less.

4. The optical film according to claim 1, wherein, Based on a thickness of 50 μm, the light transmittance of the optical film is 88.50% or more.

5. The optical film according to claim 1, wherein, Based on a thickness of 50 μm, 20 o The glossiness is from 200 GU to 250 GU.

6. The optical film according to claim 1, wherein, Based on a thickness of 50 μm, the RSPEC of the optical film is 140 GU to 190 GU.

7. A display device, comprising: a display panel; and an optical film according to any one of claims 1 to 6 disposed on the display panel.

8. A method for manufacturing an optical film, the method comprising: forming a first reaction solution using a first diamine compound, a second diamine compound, a dianhydride compound, and a dicarbonyl compound; adding a dehydrating agent and an imidization catalyst to the first reaction solution and reacting them to form a second reaction solution; processing the second reaction solution to prepare a solid-phase polymer resin; dissolving the solid-phase polymer resin to prepare a polymer resin solution; and casting the polymer resin solution, wherein the first diamine compound is 2,2'-bis(trifluoromethyl)benzidine (TFDB), the second diamine compound includes an aromatic diamine compound, the packing density of the dicarbonyl compound is 0.5 g / ml to 0.8 g / ml, Based on the total content of 100 moles of the first diamine compound and the second diamine compound, the content of the dicarbonyl compound is 80 moles or more, the content of the dianhydride compound is 20 moles or less, and Based on the total content of 100 moles of the first diamine compound and the second diamine compound, the content of the first diamine compound is 50 moles to 95 moles, and the content of the second diamine compound is 5 moles to 50 moles.

9. The method according to claim 8 further comprises: Before forming the first reaction solution, reduce the bulk density of the dicarbonyl compound.

10. The method according to claim 8, wherein, The second diamine compound includes at least one selected from bis(3-aminophenyl)sulfone (3DDS), bis(4-aminophenyl)sulfone (4DDS), 2,2-bis(3-amino-4-methylphenyl)hexafluoropropane (AMH), 9,9-bis(4-aminophenyl)fluorene (FDA), 9,9-bis(3-fluoro-4-aminophenyl)fluorene (FFDA), m-phenylenediamine (mPDA), p-methylenedianiline (pMDA), m-methylenedianiline (mMDA), 1,3-bis(3-aminophenoxy)benzene (133APB), 1,3-bis(4-aminophenoxy)benzene (134APB), 1,4-bis(4-aminophenoxy)benzene (144APB), 2,2'-bis(3-aminophenyl)hexafluoropropane (33-6F), 2,2'-bis(4-aminophenyl)hexafluoropropane (44-6F), 2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane (6FAP), 2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane (HFBAPP), bis(4-(4-aminophenoxy)phenyl)sulfone (BAPS), bis(4-(3-aminophenoxy)phenyl)sulfone (BAPSM), 2,2-bis(4-(4-aminophenoxy)phenyl)propane (BAPP), 4,4-bis(4-aminophenoxy)biphenyl (BAPB), 3,3-diamino-4,4,-dihydroxydiphenylsulfone (DABS), 2,2,-bis(3-amino-4-hydroxyphenyl)propane (BAP), 4,4'-diaminodiphenyl ether (4-ODA), and 3,3'-diaminodiphenyl ether (3-ODA).

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