Optical film comprising a polymer resin having excellent polymerization degree and display device including the same

Abstract

The present invention provides an optical film and a display device including the same, the optical film including a polymer resin including: a first repeating unit; a second repeating unit; a third repeating unit; and a fourth repeating unit, wherein the first repeating unit is an imide repeating unit from a first diamine-based compound and a dianhydride-based compound, the second repeating unit is an imide repeating unit from a second diamine-based compound and a dianhydride-based compound, the third repeating unit is an amide repeating unit from the first diamine-based compound and a dicarbonyl-based compound, and the fourth repeating unit is an amide repeating unit from the second diamine-based compound and a dicarbonyl-based compound. The first diamine-based compound is 2,2'-bis(trifluoromethyl)benzidine (TFDB), the second diamine-based compound includes an aromatic diamine-based compound, and the number of the amide repeating units including the third and fourth repeating units is at least 80% of the total number of repeating units including the first to fourth repeating units.

Description

Technical Field

[0001] This disclosure relates to an optical film comprising a polymer resin having a high degree of polymerization and a display device comprising the optical film. Background Technology

[0002] Recently, in order to reduce the thickness and weight of display devices and increase their flexibility, the use of optical films instead of glass as cover windows for display devices has been considered. For optical films to be used as cover windows for display devices, they need to possess excellent optical and mechanical properties.

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

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

[0005] Recently, polyamide-imide resins incorporating amide repeating units into polyimide resins have been developed. Films prepared using polyamide-imide resins exhibit excellent optical and mechanical properties, such as superior insolubility, chemical resistance, heat resistance, radiation resistance, and low-temperature characteristics. Polyamide-imide resins can be prepared using diamine compounds, dianhydride compounds, and dicarbonyl compounds as monomers.

[0006] However, for example, when 2,2′-bis(trifluoromethyl)benzidine (TFDB) is used as a diamine, the problem arises that during the polymerization of TFDB with a large number of dicarbonyl compounds, the dicarbonyl compounds gel due to the rigid structure of TFDB, resulting in an incomplete polymerization reaction.

[0007] Therefore, there is a need to develop a polyamide-imide resin that maintains a high degree of polymerization even when a large amount of dicarbonyl compounds are added. Summary of the Invention

[0008] Technical issues

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

[0010] Another aspect of this disclosure is to provide an optical film that exhibits excellent optical and mechanical properties.

[0011] Technical solution

[0012] According to this disclosure, the above and other objectives can be achieved by providing an optical film comprising 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 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, and 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 aromatic diamine compounds, and the sum of the number of amide repeating units comprising the third and fourth repeating units is more than 80% of the total number of repeating units comprising the first to fourth repeating units.

[0013] The ionization energy of the second diamine compound, an aromatic diamine compound, can be from 7.35 eV to 7.75 eV.

[0014] The aromatic diamine compounds of the second diamine class may contain at least one functional group selected from sulfonyl, carbonyl, methylene, propylene and halogen.

[0015] The aromatic diamine compound of the second diamine class may include at least one selected from 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′-methylenediphenylamine (MDA), 3,3′-(dimethylamino)benzophenone, 4,4′-(dimethylamino)benzophenone and benzidine tetrachloride (CIBZ).

[0016] The ratio of the number of repeating units from the first diamine compound to the number of repeating units from the second diamine compound can be from 95:5 to 65:35.

[0017] The weight-average molecular weight (Mw) of the polymer resin can be from 200,000 to 500,000.

[0018] Based on a thickness of 50 μm, the yellowness index (YI) of the optical film can be below 3.

[0019] With a thickness of 50 μm, the transmittance of the optical film can be above 88%.

[0020] Based on a thickness of 50 μm, the haze of the optical film can be below 0.5%.

[0021] According to another aspect of this disclosure, a display device is provided, including a display panel and an optical film disposed on the display panel.

[0022] Beneficial effects

[0023] In one embodiment of this disclosure, by controlling the polymerization reaction of diamine compounds and dicarbonyl compounds, an optical film containing a polymer resin with a high degree of polymerization can be provided, even when a large amount of dicarbonyl compounds are added.

[0024] One embodiment of this disclosure provides an optical film with excellent optical properties.

[0025] The optical film according to another embodiment of this disclosure exhibits excellent optical and mechanical properties, and therefore, when used as a cover window for a display device, it can effectively protect the display surface of the display device. Attached Figure Description

[0026] Figure 1 This is a cross-sectional view showing a portion of a display device according to one embodiment of the present disclosure;

[0027] Figure 2 It is shown Figure 1 An enlarged cross-sectional view of the “P” part. Detailed Implementation

[0028] The embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. However, the following embodiments are provided merely as examples to provide a clear understanding of the disclosure and do not limit its scope.

[0029] The shapes, dimensions, scales, angles, and numbers disclosed in the accompanying drawings used to describe embodiments of this disclosure are merely examples, and this disclosure is not limited to the details shown. Throughout the specification, the same reference numerals refer to the same elements. In the following description, detailed descriptions of relevant known functions or configurations will be omitted where it is determined that such detailed descriptions would unnecessarily obscure the essential points of this disclosure.

[0030] Where terms such as “comprising,” “having,” or “including” are used in this specification, other parts may also exist unless “only” is used. Unless otherwise stated, singular terms may include plural meanings. Furthermore, when interpreting an element, it is understood to include a range of errors even if it is not explicitly described.

[0031] When describing positional relationships, for example, when the positional relationship is described as "above", "over", "below", or "next", it may include cases where there is no contact between them, unless "exactly" or "directly" is used.

[0032] In this document, spatially related terms such as “below,” “under,” “lower,” “above,” and “upper” may be used to describe the relationship between a device or element as shown in the figures and another device or element. It should be understood that, in addition to the orientation depicted in the figures, spatially related terms are intended to include different orientations of the device during use or operation. For example, if a device in a figure is inverted, an element described as “below” or “under” other elements would be located “above” other elements. Therefore, the exemplary terms “below” or “under” can include the meanings of both “below” and “upper.” Similarly, the exemplary terms “above” or “upper” can include the meanings of both “above” and “below.”

[0033] When describing temporal relationships, for example, when using "after," "following," "next," or "before" to describe chronological order, non-continuous relationships may be included unless "exactly" or "directly" is used.

[0034] It should be understood that although the terms "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 this disclosure, the first element may be referred to as the second element.

[0035] It should be understood that the term "at least one" includes all combinations relating to one or more elements. For example, "at least one of the first element, the second element, and the third element" can 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 individually.

[0036] The features of the various embodiments of this disclosure can be combined or integrated with each other in part or in whole, and can interact with each other in various ways and be technically driven. The embodiments of this disclosure can be carried out independently of each other, or they can be carried out together in a related manner.

[0037] One embodiment of this disclosure provides an optical film. The optical film according to the embodiment of this disclosure comprises a polymer resin.

[0038] The polymer resin can be contained in the membrane in any of a variety of shapes and forms, for example, as a solid powder, in a dissolved state, or as a matrix that solidifies after being dissolved in a solution. Any resin can be considered the same as the polymer resin of this disclosure, regardless of its shape and form, as long as it is a resin containing the same repeating units as those in this disclosure. Typically, the polymer resin can be present in the membrane as a matrix, which is obtained by coating a polymer resin solution and drying it to form a solid.

[0039] An optical film according to one embodiment of the present disclosure may contain at least one of imide repeating units and amide repeating units. For example, an optical film according to one embodiment of the present disclosure may contain at least one of polyimide polymers, polyamide polymers, and polyamide-imide polymers.

[0040] An optical film according to one embodiment of the present disclosure may comprise an imide repeating unit formed of a diamine compound and a dianhydride compound.

[0041] An optical film according to one embodiment of the present disclosure may comprise amide repeating units formed of diamine compounds and dicarbonyl compounds.

[0042] An optical film according to one embodiment of this disclosure may comprise both amide repeating units and imide repeating units formed from diamine compounds, dianhydride compounds, and dicarbonyl compounds.

[0043] For example, an optical film according to one embodiment of the present disclosure may comprise at least one of polyimide resin, polyamide resin, and polyamide-imide resin.

[0044] According to one embodiment of this disclosure, the optical film can be any one of a polyimide film, a polyamide film, and a polyamide-imide film, but the embodiments of this disclosure are not limited thereto. Any film with light transmittance can be used as the optical film according to one embodiment of this disclosure.

[0045] According to one embodiment of the present disclosure, the polymer resin comprises a first repeating unit, a second repeating unit, a third repeating unit, and a fourth repeating unit.

[0046] 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; and the fourth repeating unit is an amide repeating unit derived from the second diamine compound and the dicarbonyl compound.

[0047] The sum of the number of amide repeating units, including the third and fourth repeating units, is more than 80% of the total number of repeating units, including the first to fourth repeating units.

[0048] As used herein, the term "repeating unit from..." refers to a plurality of monomers used to form a polymer that are linked together and arranged in a repeating manner within the polymer. This term is widely used in the art to which this disclosure pertains. For example, polyethylene is a polymer having repeating units from ethylene, having a structure in which a plurality of ethylene monomers are linked together and arranged in a repeating manner within the polyethylene polymer.

[0049] In this disclosure, the imide repeating unit of the polymer resin can be prepared from a monomer component comprising a diamine compound and a dianhydride compound. Specifically, the diamine compound and the dianhydride compound are polymerized to form an amide acid, and the amide acid is imidized to form the imide repeating unit. Alternatively, the amide repeating unit can also be prepared by polymerization of a monomer component comprising 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.

[0050] However, the polymer resin according to one embodiment of this disclosure is not limited thereto. The polymer resin according to one embodiment of this disclosure can be prepared from monomer components comprising other compounds besides the said diamine compounds, said dianhydride compounds, and said dicarbonyl compounds. Therefore, the polymer resin according to one embodiment of this disclosure may also comprise other repeating units besides imide repeating units and amide repeating units.

[0051] According to one embodiment of this disclosure, the sum of the number of amide repeating units including the third and fourth repeating units corresponds to more than 80% of the total number of repeating units including the first to fourth repeating units. Preferably, the sum of the number of amide repeating units including the third and fourth repeating units corresponds to more than 95% of the total number of repeating units including the first to fourth repeating units, more preferably more than 98%.

[0052] When the sum of the number of amide repeating units, including the third and fourth repeating units, is more than 80% of the total number of repeating units, including the first to fourth repeating units, the optical properties of the manufactured film can be maintained while its mechanical properties can be improved. That is, by including more amide repeating units than imide repeating units, a colorless and transparent optical film with improved insolubility, chemical resistance, heat resistance, radiation resistance, low-temperature properties, tensile strength, elongation, etc., is manufactured.

[0053] When a large amount of dicarbonyl compounds are added in order to form a large number of repeating amide units, the problem is that the dicarbonyl compounds gel, and therefore the polymerization reaction does not proceed sufficiently.

[0054] In this disclosure, the gelation of dicarbonyl compounds can be prevented or inhibited by using two or more different types of diamine compounds for polymerization. Therefore, the polymer resin of this disclosure comprises repeating units from at least two types of diamine compounds, including a first diamine compound and a second diamine compound.

[0055] Specifically, according to one embodiment of this 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 unit and amide repeating unit of this disclosure can be derived from TFDB and aromatic diamine compounds other than TFDB.

[0056] Because 2,2′-bis(trifluoromethyl)benzidine (TFDB), as a first diamine compound, has a specific linear and rigid structure, membranes containing repeating units from TFDB can be endowed with greatly improved mechanical properties, such as insolubility, chemical resistance, heat resistance, radiation resistance, and low-temperature properties.

[0057] However, due to the rigid structure of TFDB, the polymerization between TFDB and dicarbonyl compounds is accelerated. This rapid polymerization results in only a portion of the dicarbonyl compound reacting with the diamine compound, while the remaining portion of the dicarbonyl compound gels instead of polymerizing. This gelation of the dicarbonyl compound reduces the degree of polymerization of the resin and degrades the optical properties of the film. Therefore, it is difficult to prepare polymer resins containing a large number of repeating amide units simply by adding TFDB. According to this disclosure, a second diamine compound having a predetermined ionization energy can prevent the gelation of the dicarbonyl compound and improve the degree of polymerization of the polymer.

[0058] According to one embodiment of this disclosure, the second diamine compound includes an aromatic diamine compound.

[0059] In one embodiment of this 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 contain an aliphatic group or other substituents as part of its structure. The aromatic ring may be a monocyclic ring, a fused ring comprising a monocyclic ring directly bonded to it via a heteroatom, or a fused ring. Examples of aromatic rings may include, but are not limited to, benzene rings, biphenyl rings, naphthalene rings, anthracene rings, and fluorene rings.

[0060] According to one embodiment of this disclosure, the second diamine compound can be represented by the following chemical formula 1:

[0061] [Chemical Formula 1]

[0062] H2N-A 1 -NH2

[0063] Among them, A 1 This indicates a divalent aromatic organic group. An aromatic organic group is an organic group in which π electrons are delocalized, resulting in alternating single and double bonds forming a ring. For example, A... 1 This may include divalent aromatic organic groups having 4 to 40 carbon atoms. The hydrogen atoms in the aromatic organic groups of Formula 1 may be replaced by halogens, hydrocarbon groups, or hydrocarbon groups substituted with halogens. Here, the hydrocarbon group or the hydrocarbon group substituted with a halogen may have 1 to 8 carbon atoms. For example, A 1 The hydrogen in it can be replaced by -F, -CH3, -CF3, etc.

[0064] Optical films made from diamine compounds in which hydrogen atoms are replaced by fluorine-substituted hydrocarbon groups can be endowed with excellent light transmittance and excellent processability.

[0065] A in chemical formula 1 1 Yes, for example, including structures represented by any of the following chemical formulas.

[0066]

[0067] In the chemical formula above, * indicates a bonding position. In the chemical formula above, X can be any of the following: single bond, O, S, SO2, CO, CH2, C(CH3)2, and C(CF3)2. Although there are no particular restrictions on the bonding position of X on each ring, the bonding position of X can be, for example, meta or para on each ring.

[0068] According to one embodiment of this disclosure, the second diamine compound includes an aromatic diamine compound with an ionization energy of 7.35 eV to 7.75 eV.

[0069] Since the second diamine compounds also include aromatic diamine compounds with ionization energies of 7.35 eV to 7.75 eV (excluding TFDB), they can polymerize with a large number of dicarbonyl compounds at a high degree of polymerization. When the ionization energy of the aromatic diamine compounds is between 7.35 eV and 7.75 eV, the polymerization rate between the diamine compounds and dicarbonyl compounds can be controlled. Even with a large number of dicarbonyl compounds, the polymerization reaction can proceed smoothly, and the degree of polymerization of the resin can be increased.

[0070] When the ionization energy of aromatic diamine compounds is less than 7.35 eV, the electron-donating effect of the diamine compounds increases, and their charge-transfer complexation effect also increases, leading to a deterioration in optical properties. Furthermore, the increased reactivity increases the reaction rate, thus causing the dicarbonyl compounds to gel.

[0071] On the other hand, when the ionization energy of aromatic diamine compounds exceeds 7.55 eV, the degree of polymerization decreases due to low reactivity. Therefore, relatively short polymer chains are formed, and the number of terminal groups in the polymer chains increases. As the number of terminal groups in the polymer chains increases, the physical properties of the resin deteriorate.

[0072] According to one embodiment of this disclosure, the aromatic diamine compound of the second diamine compound may contain at least one functional group selected from sulfonyl, carbonyl, methylene, propylene and halogen.

[0073] Sulfonyl, carbonyl, methylene, propylene, and halogen substituents control the movement of electrons in compounds. Therefore, by including at least one of sulfonyl, carbonyl, methylene, propylene, and halogen substituents, second diamine compounds can be endowed with ionization energies of 7.35 eV to 7.75 eV. Thus, the reactivity and reaction rate of polymerization reactions with dicarbonyl compounds can be appropriately tuned.

[0074] According to one embodiment of this 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-aminophenyl)hexafluoropropane (3,3′-6F), 2,2-bis(4-aminophenyl)hexafluoropropane (4,4′-6F), 4,4′-methylenediphenylamine (MDA), 3,3′-(dimethylamino)benzophenone, 4,4′-(dimethylamino)benzophenone, and benzidine tetrachloride (CIBZ). All the aromatic diamine compounds listed above are diamine compounds with ionization energies of 7.35 eV to 7.75 eV.

[0075] According to one embodiment of this 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) can be in the range of 95:5 to 65:35. Here, the term "repeating units from the first diamine compound (or the second diamine compound)" is intended to include both imide repeating units and amide repeating units from the first diamine compound (or the second diamine compound).

[0076] Regarding the ratio of repeating units from the first diamine compound to repeating units from the second diamine compound, when the ratio of repeating units from the first diamine compound increases to greater than 95:5, the ratio of repeating units from TFDB and dicarbonyl compounds increases, and the haze increases. On the other hand, when the ratio of repeating units from the second diamine compound increases to greater than 65:35, the heat resistance and strength of the film decrease.

[0077] In one embodiment of this disclosure, the dianhydride compound can be represented by the following chemical formula 2:

[0078] [Chemical Formula 2]

[0079]

[0080] Among them, A 2 This indicates a tetravalent organic group. For example, A 2 This may include tetravalent organic groups having 4 to 40 carbon atoms. The hydrogen atoms in the organic groups of Formula 2 may be replaced by halogens, hydrocarbon groups, or hydrocarbon groups substituted with halogens. Here, the hydrocarbon group or the hydrocarbon group substituted with a halogen may have 1 to 8 carbon atoms.

[0081] A in chemical formula 2 2 Yes, for example, including structures represented by any of the following chemical formulas.

[0082]

[0083] In the chemical formulas above, * indicates a bonding position. In the chemical formulas above, Z can independently be a single bond, O, S, SO2, CO, or (CH2). n (C(CH3)2) n and (C(CF3)2) n Any one of the following, and n can be an integer from 1 to 5. Although there are no particular restrictions on the position of Z on each ring, the position of Z can be, for example, interposition or opposition on each ring.

[0084] In one embodiment of this disclosure, the dianhydride compound may include a selection from 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA), biphenyltetracarboxylic dianhydride (BPDA), naphthalenetetracarboxylic dianhydride (NTDA), diphenylsulfonetetracarboxylic dianhydride (DSDA), 4-(2,5-oxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic anhydride (TDA), pyromellitic dianhydride (PMDA), benzophenonetetracarboxylic dianhydride (BTDA), oxophthalic anhydride (ODPA), bis(carboxyphenyl)dimethylsilane dianhydride (SiDA), bis(dicarboxyphenoxy)diphenyl sulfide dianhydride (BDSDA), and diphenylsulfonetetracarboxylic acid. One or more of the following dianhydrides: SO2DPA, isopropylidene diphenoxybis(phthalic anhydride) (BPADA), 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA), 1,2,3,4-cyclopentanetetracarboxylic dianhydride (CPDA), 1,2,3,4-cyclohexanetetracarboxylic dianhydride (CHDA), 1,2,3,4-butanetetracarboxylic dianhydride, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, dicyclohexyl-3,4,3″,4″-tetracarboxylic dianhydride, tetrahydrofuran-2,3,4,5-tetracarboxylic dianhydride, and bicyclo[2.2.2]octane-2,3,5,6-tetracarboxylic 2,3:5,6-dianhydride, but this disclosure is not limited thereto.

[0085] The monomers used in the manufacture of the optical film according to one embodiment of the present disclosure may include, for example, a variety of dianhydride compounds.

[0086] Optical films made from dianhydride compounds in which hydrogen atoms are replaced by fluorine-substituted hydrocarbon groups can be endowed with excellent light transmittance and excellent processability.

[0087] According to one embodiment of this disclosure, the dicarbonyl compound can be represented by the following chemical formula 3:

[0088] [Chemical Formula 3]

[0089]

[0090] Among them, A 3 This indicates a divalent organic group. For example, A 3 This may include divalent organic groups having 4 to 40 carbon atoms. The hydrogen atoms in the organic groups of Formula 3 may be replaced by halogens, hydrocarbon groups, or fluorine-substituted hydrocarbon groups. Here, the hydrocarbon group or fluorine-substituted hydrocarbon group may have 1 to 8 carbon atoms. For example, A 3 The hydrogen in it can be replaced by -F, -CH3, -CF3, etc.

[0091] A in chemical formula 3 3Yes, for example, including structures represented by any of the following chemical formulas.

[0092]

[0093] In the chemical formula above, * indicates a bonding position. In the chemical formula above, Y can independently be any one of a single bond, O, S, SO2, CO, CH2, C(CH3)2, and C(CF3)2. Although there are no particular restrictions on the bonding position of Y on each ring, the bonding position of Y can be, for example, meta or para on each ring.

[0094] According to one embodiment of this disclosure, the dicarbonyl compound may include at least one selected from terephthaloyl chloride (TPC), isophthaloyl chloride (IPC), biphenyl dicarbonyl chloride (BPDC), 4,4′-oxobisbenzoyl chloride (OBBC), and naphthalene dicarbonyl dichloride (NTDC).

[0095] According to one embodiment of the present disclosure, the polymer resin may comprise a first repeating unit represented by chemical formula 4 below and a second repeating unit represented by chemical formula 5 below:

[0096] [Chemical Formula 4]

[0097]

[0098] Among them, A 2 As mentioned above,

[0099] [Chemical Formula 5]

[0100]

[0101] Among them, A 1 and A 2 As stated above.

[0102] According to one embodiment of the present disclosure, the polymer resin may comprise a third repeating unit represented by chemical formula 6 below and a fourth repeating unit represented by chemical formula 7 below:

[0103] [Chemical Formula 6]

[0104]

[0105] Among them, A 3 As mentioned above,

[0106] [Chemical Formula 7]

[0107]

[0108] Among them, A 1 and A3 As stated above.

[0109] According to one embodiment of this disclosure, the weight-average molecular weight (Mw) of the polymer resin of this disclosure can be from 200,000 to 500,000.

[0110] The weight-average molecular weight of the polymer resin can be measured using GPC (Alliance e2695 / 2414 RID, Waters) under the following conditions.

[0111] Detector: 2414 RID, Waters

[0112] Mobile phase: 10 mM LiBr in DMAc

[0113] Sample concentration: 0.25% (w / w) in DMAc.

[0114] Column and detector temperature: 50℃

[0115] Flow rate: 1.0 ml / min

[0116] The high reaction rate with diamine compounds, particularly TFDB, causes gelation of dicarbonyl compounds, which reduces the degree of polymerization of polymer resins containing a large number of amide repeating units. Weight-average molecular weight is proportional to the degree of polymerization. That is, as the degree of polymerization decreases, the weight-average molecular weight of the polymer resin also decreases.

[0117] When the weight-average molecular weight of a polymer resin is less than 200,000, the degree of polymerization decreases, the number of end groups in the polymer chain increases, and the physical properties of the polymer resin deteriorate. On the other hand, it is difficult to prepare polymer resins with a weight-average molecular weight greater than 500,000 in the process. The weight-average molecular weight of a polymer resin is adjusted by controlling the polymerization viscosity during the polymerization process. Resins with a weight-average molecular weight exceeding 500,000 are unfavorable for processing because the polymerization viscosity is very high, which leads to a decrease in the fluidity of the reaction solution, making it difficult to control and handle, and requiring a large amount of solvent to redissolve the polymer resin.

[0118] According to one embodiment of this disclosure, the optical film is transparent. Furthermore, the optical film is flexible. For example, the optical film according to one embodiment of this disclosure is bendable, foldable, or rollable. The optical film can possess excellent mechanical and optical properties.

[0119] According to one embodiment of this disclosure, the optical film may have a thickness sufficient to protect the display panel. For example, the thickness of the optical film may be from 10 μm to 100 μm.

[0120] According to one embodiment of this disclosure, based on a thickness of 50 μm, the average transmittance of the optical film in the visible light region, as measured using a UV spectrophotometer, can be above 88%.

[0121] The average transmittance of the optical film can be measured using a spectrophotometer (CM-3700D, KONICA MINOLTA) in the wavelength range of 360 nm to 740 nm.

[0122] According to one embodiment of this disclosure, based on a thickness of 50 μm, the yellowness index of the optical film can be below 3.

[0123] The yellowness index of the optical film can be measured using a spectrophotometer (CM-3700D, KONICAMINOLTA) according to the ASTM E313 standard.

[0124] According to one embodiment of this disclosure, based on a thickness of 50 μm, the haze of the optical film can be below 0.5%.

[0125] The haze of the optical film can be determined by cutting the manufactured optical film into 50mm×50mm samples, measuring it five times using a haze meter (model name: HM-150, manufactured by Murakami Color Research Laboratory) according to ASTM D1003, and taking the average of the five values ​​as the haze of the optical film.

[0126] Figure 1 This is a cross-sectional view showing a portion of a display device 200 according to another embodiment. Figure 2 yes Figure 1 An enlarged cross-sectional view of the "P" section in the image.

[0127] Reference 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.

[0128] Reference Figure 1 and Figure 2 The display panel 501 includes: a substrate 510; a thin-film transistor (TFT) on the substrate 510; and an organic light-emitting device (OLED) 570 connected to the TFT. The OLED 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 is an organic light-emitting display device.

[0129] The substrate 510 can be formed of glass or plastic. Specifically, the substrate 510 can be formed of plastic such as polymer resin or optical film. Although not shown, a buffer layer can be provided on the substrate 510.

[0130] A thin-film transistor (TFT) is disposed on a substrate 510. The TFT includes: a semiconductor layer 520; a gate electrode 530 that is insulated from and at least partially overlaps the semiconductor layer 520; a source electrode 541 connected to the semiconductor layer 520; and a drain electrode 542 that is spaced apart from the source electrode 541 and connected to the semiconductor layer 520.

[0131] Reference Figure 2 A gate insulating layer 535 is disposed between the gate electrode 530 and the semiconductor layer 520. An interlayer insulating layer 551 may be disposed on the gate electrode 530, and the source electrode 541 and the drain electrode 542 may be disposed on the interlayer insulating layer 551.

[0132] A planarization layer 552 is provided on the thin-film transistor TFT to planarize the top of the thin-film transistor TFT.

[0133] The first electrode 571 is disposed on the planarization layer 552. The first electrode 571 is connected to the thin-film transistor (TFT) through a contact hole disposed in the planarization layer 552.

[0134] A dam layer 580 is disposed on a planarization layer 552 in a portion of the first electrode 571 to define a pixel region or a light-emitting region. For example, the dam layer 580 is disposed in a matrix at the boundaries between multiple pixels to define individual pixel regions.

[0135] An organic light-emitting layer 572 is disposed on the first electrode 571. The organic light-emitting layer 572 may also be disposed on the diaphragm layer 580. The organic light-emitting layer 572 may include a single light-emitting layer or two light-emitting layers stacked in the vertical direction. The organic light-emitting layer 572 can emit light of any color among red, green, and blue, and may also emit white light.

[0136] The second electrode 573 is disposed on the organic light-emitting layer 572.

[0137] The first electrode 571, the organic light-emitting layer 572, and the second electrode 573 can be stacked to form an organic light-emitting device 570.

[0138] 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.

[0139] A thin-film encapsulation layer 590 may be disposed on the second electrode 573. The thin-film encapsulation layer 590 may include at least one organic layer and at least one inorganic layer, and the at least one organic layer and the at least one inorganic layer may be disposed alternately.

[0140] An optical film 100 is disposed on a display panel 501 having the above-described stacked structure.

[0141] The following will briefly describe a method for manufacturing an optical film according to another embodiment of the present disclosure.

[0142] A method for manufacturing an optical film according to one embodiment of the present disclosure includes: preparing a polymer resin, dissolving the polymer resin in a solvent to prepare a polymer resin solution, and using the polymer resin solution to manufacture an optical film.

[0143] The preparation of polymer resins can be carried out by polymerization of monomers used to form the polymer resin, followed by imidization. The polymer resin can be prepared from a monomer component comprising a first diamine compound, a second diamine compound, a dianhydride compound, and a dicarbonyl compound. In this disclosure, there are no restrictions on the order or method of addition of the monomers. For example, the dianhydride compound and the dicarbonyl compound can be sequentially added to a solution in which the diamine compound is dissolved, and the resulting mixture can be polymerized. Alternatively, to avoid randomness, the first diamine compound, the dianhydride compound, the second diamine compound, and the dicarbonyl compound can be added in the stated order, or the second diamine compound, the dianhydride compound, the first diamine compound, and the dicarbonyl compound can be added in the stated order, followed by polymerization.

[0144] More specifically, the polymer resin can be prepared by polymerization and imidization of monomers comprising a first diamine compound, a second diamine compound, a dianhydride compound, and a dicarbonyl compound. The imide repeating unit can be prepared by polymerization and imidization of monomers comprising the first and second diamine compounds and a dianhydride compound. Furthermore, the amide repeating unit can be prepared by polymerization of monomers comprising the first and second diamine compounds and a dicarbonyl compound.

[0145] Therefore, the polymer resin according to another embodiment of this disclosure may have imide repeating units and amide repeating units.

[0146] The imide repeating unit and the amide repeating unit can be prepared separately and then copolymerized. Alternatively, the imide repeating unit can be prepared first, and then a dicarbonyl compound can be added to prepare the amide repeating unit; or the amide repeating unit can be prepared first, and then a dianhydride compound can be added to prepare the imide repeating unit. The polymer resin disclosed herein is not limited to the order of formation of the repeating units (the order of addition of monomers).

[0147] According to another embodiment of this disclosure, the amount of dicarbonyl compound added can be 80 mol% or more, based on the total molar amount of dianhydride and dicarbonyl compounds. Therefore, the polymer resin of this disclosure contains 80% or more amide repeating units. Preferably, the amount of dicarbonyl compound added can be 95 mol% or more, more preferably 98 mol% or more, based on the total molar amount of dianhydride and dicarbonyl compounds.

[0148] According to another embodiment of this disclosure, the first diamine compound is 2,2′-bis(trifluoromethyl)benzidine (TFDB).

[0149] According to another embodiment of this disclosure, the second diamine compound includes an aromatic diamine compound. In the following description, to avoid repetition, the description of the above configuration is omitted.

[0150] 2,2′-bis(trifluoromethyl)benzidine (TFDB) can be used as the first diamine compound, aromatic diamine compounds of the above chemical formula 1 can be used as the second diamine compound, compounds of the above chemical formula 2 can be used as dianhydride compounds, and compounds of the above chemical formula 3 can be used as dicarbonyl compounds.

[0151] According to another embodiment of this disclosure, the ionization energy of the aromatic diamine compound of the second diamine compound can be from 7.35 eV to 7.75 eV.

[0152] According to another embodiment of this disclosure, the aromatic diamine compound of the second diamine compound may contain at least one functional group selected from sulfonyl, carbonyl, methylene, propylene and halogen.

[0153] According to another embodiment of this disclosure, the aromatic diamine compound of 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-aminophenyl)hexafluoropropane (3,3′-6F), 2,2-bis(4-aminophenyl)hexafluoropropane (4,4′-6F), 4,4′-methylenediphenylamine (MDA), 3,3′-(dimethylamino)benzophenone (3,3′-CO), 4,4′-(dimethylamino)benzophenone (4,4′-CO), and benzidine tetrachloride (CIBZ).

[0154] According to another embodiment of this disclosure, the ratio of the amount of the first diamine compound to the amount of the second diamine compound can be from 95:5 to 65:35.

[0155] According to another embodiment of this disclosure, the solvent used to prepare the polymer resin solution can be, for example, a polar aprotic organic solvent, such as N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), 1-methyl-2-pyrrolidone (NMP), m-cresol, tetrahydrofuran (THF), chloroform, methyl ethyl ketone (MEK), or mixtures thereof. However, the solvent according to one embodiment of this disclosure is not limited thereto, and other solvents may be used.

[0156] The present disclosure will now be described in more detail with reference to exemplary embodiments. However, the following preparation examples and embodiments should not be construed as limiting the scope of the present disclosure.

[0157] <Example 1>

[0158] 313.34 g of N,N-dimethylacetamide (DMAc) was added to a 500 mL reactor equipped with a stirrer, nitrogen injector, dropping funnel, temperature controller, and cooler, while nitrogen gas was passed through the reactor. The reactor temperature was then adjusted to 25 °C, and 24.02 g (0.075 mol) of TFDB (as the first diamine compound) was dissolved therein, along with 6.21 g (0.025 mol) of bis(3-aminophenyl)sulfone (3DDS) (as the second diamine compound), and the resulting solution was maintained at 25 °C. 0.89 g (0.002 mol) of 6FDA was added to the resulting diamine compound solution, and the solution was stirred for 2 hours until completely dissolved. The reactor temperature was then lowered to 10 °C, and 19.90 g (0.098 mol) of terephthaloyl chloride (TPC) was added, completely dissolved, and reacted for 1 hour. The temperature was then raised to 25 °C. 0.35 g of pyridine and 0.45 g of acetic anhydride were added to the resulting reaction solution, and the mixture was stirred at 80 °C for 30 minutes. Excess methanol was added dropwise to obtain polyamide-imide powder. The powder was filtered under reduced pressure, dried, and redissolved in DMAc to prepare a polymer resin solution with a solid concentration of 14% by weight.

[0159] The obtained polymer resin solution is cast. A casting substrate is used for casting. There are no particular limitations on the type of casting substrate. Glass substrates, stainless steel (SUS) substrates, Teflon substrates, etc., can be used as casting substrates. According to one embodiment of this disclosure, an organic substrate can be used as the casting substrate.

[0160] Specifically, the obtained polymer resin solution is coated onto a glass substrate, cast, and dried with hot air at 80°C for 20 minutes and then at 120°C for 20 minutes to produce a film. The produced film is then peeled off the glass substrate and fixed to a frame with pins.

[0161] The frame with the film fixed 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 was completed.

[0162] <Examples 2 to Examples 12>

[0163] The optical films of Examples 2 to 12 were manufactured in the same manner as in Example 1, except that the amount of the first diamine (TFDB) added, the type and amount of the second diamine added, the type and amount of the dianhydride compound added, and the type and amount of the dicarbonyl compound added were changed.

[0164] The detailed descriptions of the amount of the first diamine (TFDB) added in Examples 1 to 12, the type and amount of the second diamine added, the type and amount of the dianhydride compound added, and the type and amount of the dicarbonyl compound added are shown in Table 1 below.

[0165] <Example 13>

[0166] Except for variations in the amount of the first diamine (TFDB), the type and amount of the second diamine, the type and amount of the dianhydride compound, and the type and amount of the dicarbonyl compound, the film was manufactured in the same manner as in Example 1. The manufactured film was then peeled off the glass substrate and secured to a frame with pins. The frame with the film attached was placed in an oven and dried with hot air at a constant temperature of 250°C for 10 minutes. As a result, the 50 μm thick optical film of Example 13 was completed.

[0167] The detailed description of the amount of the first diamine (TFDB) added, the type and amount of the second diamine added, the type and amount of the dianhydride compound added, and the type and amount of the dicarbonyl compound added in Example 13 is shown in Table 1 below.

[0168] <Comparative Examples 1 to 3>

[0169] The optical films of Comparative Examples 1 to 3 were manufactured in the same manner as in Example 1, except that the amount of the first diamine (TFDB), the type and amount of the second diamine, the type and amount of the dianhydride compound, and the type and amount of the dicarbonyl compound were changed.

[0170] The detailed descriptions of the amount of the first diamine (TFDB) added, the type and amount of the second diamine added, the type and amount of the dianhydride compound added, and the type and amount of the dicarbonyl compound added in Comparative Examples 1 to 3 are shown in Table 1 below.

[0171] <Comparative Examples 4 and 5>

[0172] Except for changing the amount of the first diamine (TFDB), the type and amount of the second diamine, and the type and amount of the dicarbonyl compound, the optical films of Comparative Examples 4 and 5 were manufactured in the same manner as in Example 1. In Comparative Examples 4 and 5, dianhydride compounds were not used; therefore, the steps of purification with chemical curing agents and methanol were omitted.

[0173] The detailed descriptions of the amount of the first diamine (TFDB), the type and amount of the second diamine, and the type and amount of the dicarbonyl compound added in Comparative Examples 4 and 5 are shown in Table 1 below.

[0174] [Table 1]

[0175]

[0176]

[0177] 3DDS: Bis(3-aminophenyl)sulfone

[0178] 4DDS: bis(4-aminophenyl)sulfone

[0179] 3,3′-6F: 2,2-bis(3-aminophenyl)hexafluoropropane

[0180] 4,4′-6F: 2,2-bis(4-aminophenyl)hexafluoropropane

[0181] pPDA: p-phenylenediamine

[0182] 8FODA: O-4,4′-bis(2,3,5,6-tetrafluoroaniline)

[0183] TPC: Terephthaloyl chloride

[0184] BPDC: 4,4′-Biphenyldicarboxylic acid chloride

[0185] CBDA: 1,2,3,4-Cyclobutanetetracarboxylic dianhydride

[0186] <Measurement Example>

[0187] The following measurements were performed on the polymer resins and films manufactured in Examples 1 to 13 and Comparative Examples 1 to 5.

[0188] 1) Weight-average molecular weight of polymer resin: The weight-average molecular weight of polymer resin was measured using GPC (Alliance e2695 / 2414 RID, Waters) under the following conditions.

[0189] Detector: 2414 RID, Waters

[0190] Mobile phase: 10 mM LiBr in DMAc

[0191] Sample concentration: 0.25% (w / w) in DMAc.

[0192] Column and detector temperature: 50℃

[0193] Flow rate: 1.0 ml / min

[0194] 2) Yellowness Index (YI): The yellowness index is measured using a spectrophotometer (CM-3700D, KONICAMINOLTA) according to ASTM E313 standard.

[0195] 3) Transmittance (%): The average transmittance at wavelengths from 360 nm to 740 nm was measured using a spectrophotometer (CM-3700D, KONICA MINOLTA).

[0196] 4) Haze: The haze was determined by cutting the manufactured optical film into 50mm × 50mm samples and performing five measurements using a haze meter (model name: HM-150, manufactured by Murakami Color Research Laboratory) according to ASTM D1003. The average of the five values ​​was taken as the haze of the optical film.

[0197] The measurement results are shown in Table 2 below.

[0198] [Table 2]

[0199]

[0200] As can be seen from the measurement results in Table 2, Examples 1 to 13 of this disclosure have high weight-average molecular weight and excellent yellowness, transmittance and haze.

[0201] However, in Comparative Examples 1 and 4, films could not be manufactured due to the gelation of dicarbonyl compounds. In Comparative Example 2, the resin had a low weight-average molecular weight, high yellowness index and haze, and low transmittance, resulting in poor visibility. In Comparative Example 3, the resin had a high weight-average molecular weight, but its yellowness index and haze were very high, and its transmittance was very low. In Comparative Example 5, the resin had a high weight-average molecular weight, but its yellowness index was high and its transmittance was low.

[0202] [Explanation of Reference Figures]

[0203] 100: Optical film

[0204] 200: Display device

[0205] 501: Display panel

Claims

1. An optical film comprising 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 first repeating unit being an imide repeating unit from a first diamine-based compound and a dianhydride-based compound, the second repeating unit being an imide repeating unit from a second diamine-based compound and the dianhydride-based compound, the third repeating unit being an amide repeating unit from the first diamine-based compound and a dicarbonyl-based compound, the fourth repeating unit being an amide repeating unit from the second diamine-based compound and the dicarbonyl-based compound, wherein the first diamine-based compound is 2,2'-bis(trifluoromethyl)benzidine (TFDB), and the second diamine-based compound comprises an aromatic diamine-based compound, wherein the aromatic diamine-based compound of the second diamine-based compound comprises 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′-(dimethylamino)benzophenone, 4,4′-(dimethylamino)benzophenone, and tetrachlorobenzidine (CIBZ), a sum of the number of the amide repeating units comprising the third repeating unit and the fourth repeating unit is 80% or more of a total number of the repeating units comprising the first to fourth repeating units.

2. The optical film of claim 1, wherein, the aromatic diamine-based compound of the second diamine-based compound has an ionization energy of 7.35 eV to 7.75 eV.

3. The optical film of claim 1, wherein, the aromatic diamine-based compound of the second diamine-based compound comprises at least one functional group selected from the group consisting of a sulfonyl group, a carbonyl group, a methylene group, a propylene group, and a halogen.

4. The optical film of claim 1, wherein, a ratio of the number of the repeating units from the first diamine-based compound to the number of the repeating units from the second diamine-based compound is 95:5 to 65:

35.

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

6. The optical film of claim 1, wherein, the optical film has a yellow index (Y.I.) of 3 or less based on a thickness of 50 µm.

7. The optical film of claim 1, wherein, the optical film has a light transmittance of 88% or more based on a thickness of 50 µm.

8. The optical film of claim 1, wherein, the optical film has a haze of 0.5% or less based on a thickness of 50 µm. 9.A display device comprising: a display panel; and the optical film according to any one of claims 1 to 8 disposed on the display panel.

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