Eco-friendly polyimide-based film and method for manufacturing same

Abstract

An embodiment of the present invention relates to an eco-friendly polyimide-based film that does not include a perfluoroalkyl group, wherein the polyimide-based film includes at least one of an imide repeating unit and an amide repeating unit, the imide repeating unit is formed by a reaction of a diamine compound and a dianhydride compound, the amide repeating unit is formed by a reaction of a diamine compound and a dicarbonyl compound, and the diamine compound includes a compound represented by chemical formula 1.

Description

Eco-friendly polyimide film and method for manufacturing the same

[0001] The present invention relates to an eco-friendly polyimide-based film that does not contain a perfluoroalkyl group and a method for manufacturing the same.

[0002] Polyimide resins possess characteristics such as high heat resistance, oxidation resistance, radiation resistance, low-temperature properties, and chemical resistance, making them widely used in electronic products, optical devices, semiconductors, automobiles, aircraft, and spacecraft. Additionally, polyimide films manufactured in film form are also used as cover windows for display devices.

[0003] Recently, research has been conducted to improve the optical properties of polyimide resins, and polyimide resins with excellent optical properties are being developed without significantly degrading mechanical and thermal properties.

[0004] Polyimide-based films possess excellent mechanical properties, but they exhibit a yellow color due to the charge-transfer complex (CT-Complex) effect. To prevent or minimize the yellowing of polyimide-based films, they are typically manufactured using fluorine-based raw materials.

[0005] Perfluorinated compound groups contained in fluorine-based raw materials, such as -CF2- or -CF3, have strong bonding forces and do not decompose easily, causing environmental pollution problems. Therefore, research is needed on a technology to manufacture polyimide-based films using raw materials that do not contain perfluorinated compound groups in order to prevent environmental pollution.

[0006] One embodiment of the present invention aims to provide a polyimide-based film that does not contain a perfluoroalkyl group.

[0007] One embodiment of the present invention aims to provide a technology for manufacturing a polyimide-based film using a monomer that does not contain a perfluoroalkyl group.

[0008] One embodiment of the present invention aims to provide a polyimide-based film having excellent mechanical properties and excellent optical properties, even when manufactured using a monomer that does not contain a perfluoroalkyl group.

[0009] One embodiment of the present invention aims to provide a polyimide-based film having low yellowness and high light transmittance, even when manufactured using a monomer that does not contain a perfluoroalkyl group.

[0010] To solve the above problem, one embodiment of the present invention provides a polyimide-based film comprising at least one of an amide repeating unit and an amide repeating unit, wherein the imide repeating unit is formed by the reaction of a diamine compound and a dianhydride compound, the amide repeating unit is formed by the reaction of a diamine compound and a dicarbonyl compound, and the diamine compound is a compound represented by the following chemical formula 1.

[0011] [Chemical Formula 1]

[0012]

[0013] Here, R1 to R8 of the above chemical formula 1 each include at least one of hydrogen (H), a methyl group (-CH3), and an ethyl group (-CH2CH3).

[0014] Each of the above imide repeating unit and amide repeating unit may not include a perfluoroalkyl group.

[0015] The above perfluoroalkyl group may include *-CF3 and *-CF2-*. Here, *- and -* each mean bonded with other elements.

[0016] At least one of R1 to R8 of the above chemical formula 1 may include a methyl group.

[0017] At least one of R1 to R4 of the above chemical formula 1 may include a methyl group, and at least one of R5 to R8 of the above chemical formula 1 may include a methyl group.

[0018] The compound represented by the above chemical formula 1 may include at least one of the compounds represented by the following chemical formulas 2 to 4.

[0019] [Chemical Formula 2]

[0020]

[0021] [Chemical Formula 3]

[0022]

[0023] [Chemical Formula 4]

[0024]

[0025] The above dicarbonyl compound may have an aromatic ring.

[0026] The above dicarbonyl compound may have a rotatable group.

[0027] The above dicarbonyl compound may include at least one of the compound represented by the following chemical formula 5 and the compound represented by the following chemical formula 6.

[0028] [Chemical Formula 5]

[0029]

[0030] [Chemical Formula 6]

[0031]

[0032] The above dianhydride compound may include a compound represented by the following chemical formula 7.

[0033] [Chemical Formula 7]

[0034]

[0035] Here, R9 to R12 of the above chemical formula 7 each include at least one of hydrogen (H), a methyl group (-CH3), and an ethyl group (-CH2CH3).

[0036] At least one of R9 to R12 of the above chemical formula 7 may include a methyl group.

[0037] The compound represented by the above chemical formula 7 may include at least one of the compounds represented by the following chemical formulas 8 to 12.

[0038] [Chemical Formula 8]

[0039]

[0040] [Chemical Formula 9]

[0041]

[0042] [Chemical Formula 10]

[0043]

[0044] [Chemical Formula 11]

[0045]

[0046] [Chemical Formula 12]

[0047]

[0048] Based on the molar amount, the content of the dicarbonyl compound may be 10 mol% or more with respect to the total content of the dicarbonyl compound and the dianhydride compound.

[0049] The above polyimide-based film may have a yellowness of 8.0 or less based on a thickness of 50 μm.

[0050] The above polyimide-based film can have a light transmittance of 85% or more at a wavelength of 380 to 780 nm.

[0051] The above polyimide-based film may have a haze of 0.8% or less based on a thickness of 50㎛.

[0052] The above polyimide-based film can have a Young's modulus of 4.0 GPa or more based on a thickness of 50 μm.

[0053] The above polyimide-based film can have an elongation of 10% or more based on a thickness of 50㎛.

[0054] According to one embodiment of the present invention, a polyimide-based film can be manufactured using a monomer that does not contain a perfluoroalkyl group, so environmental pollution can be prevented.

[0055] According to one embodiment of the present invention, an eco-friendly polyimide-based film that does not contain a perfluoroalkyl group can be manufactured.

[0056] A polyimide-based film according to one embodiment of the present invention does not contain perfluoroalkyl groups, so it has eco-friendly characteristics, while also having excellent mechanical properties and excellent optical properties.

[0057] FIG. 1 is a cross-sectional view of a part of a display device according to another embodiment of the present invention.

[0058] Figure 2 is an enlarged cross-sectional view of the "P" portion of Figure 1.

[0059] Embodiments of the present invention are described in detail below. However, the embodiments described below are presented for the purpose of facilitating a clear understanding of the present invention and are merely examples of embodiments of the present invention.

[0060] In describing the present invention, if it is determined that a detailed description of related known technology may unnecessarily obscure the essence of the present invention, such detailed description may be omitted.

[0061] Where terms such as "includes," "has," or "consists of" are used in this specification, other parts may be added unless the expression "only" is used. Where a component is expressed in the singular, it includes the plural unless specifically stated otherwise. Furthermore, in interpreting a component, it is interpreted to include a margin of error even without separate explicit description.

[0062] In the case of describing a positional relationship, for example, when the positional relationship between two parts is described using expressions such as 'on,' 'upper,' 'lower,' or 'next to,' one or more other parts may be located between the two parts unless expressions such as 'immediately' or 'directly' are used.

[0063] Spatially relative terms such as "below" or "beneath," "lower," "above," and "upper" may be used to facilitate the description of the relationship between one element or component and another, as illustrated in the drawings. Spatially relative terms should be understood as terms that include different orientations of the element during use or operation, in addition to the orientations illustrated in the drawings. For example, if an element illustrated in the drawings is flipped, the element described as "below" or "beneath" of another element may be placed "above" of that other element. Therefore, the exemplary term "below" may include both the lower and upper directions. Similarly, the exemplary terms "above" or "upper" may include both the upper and lower directions.

[0064] In the case of an explanation of a temporal relationship, for example, when the temporal sequence is explained using expressions such as 'after', 'following', 'next', or 'before', it may include cases where the sequence is not continuous unless expressions such as 'immediately' or 'directly' are used.

[0065] Although terms such as "first," "second," etc. are used to describe various components, these components are not limited by these terms. These terms are used merely to distinguish one component from another. Accordingly, the first component mentioned below may be the second component within the technical scope of the present invention.

[0066] The term “at least one” should be understood to include all combinations that can be presented from one or more related items. For example, the meaning of “at least one of the first item, the second item, and the third item” may mean not only the first item, the second item, or the third item individually, but also all combinations of items that can be presented from two or more of the first item, the second item, and the third item.

[0067] The features of each of the various embodiments of the present invention may be combined or combined with one another, either partially or wholly, and may technically enable various interlocking and operation. Each embodiment may be implemented independently of one another or may be implemented together in an associated relationship.

[0068] One embodiment of the present invention provides a polyimide-based film (100) that does not contain a perfluoroalkyl group.

[0069] A polyimide-based film (100) according to one embodiment of the present invention comprises at least one of an imide repeating unit and an amide repeating unit. The imide repeating unit may be formed by the reaction of a diamine compound and a dianhydride compound. The imide repeating unit does not include a perfluoroalkyl group. The amide repeating unit may be formed by the reaction of a diamine compound and a dicarbonyl compound. The amide repeating unit does not include a perfluoroalkyl group.

[0070] For example, a polyimide-based film (100) may be manufactured from monomer components comprising at least one of a diamine compound, a dianhydride compound, and a dicarbonyl compound. "Monomer components" may refer to all of the plurality of monomers used in the manufacture of the polyimide-based film. The monomer components may be in a mixed state of the plurality of monomers. However, the state of the monomer components is not limited thereto, and the monomer components may remain in an unmixed state and then be sequentially mixed during the manufacturing process of the polyimide-based film.

[0071] A polyimide-based film (100) according to one embodiment of the present invention may include an imide repeating unit. The polyimide-based film (100) may include an amide repeating unit. The polyimide-based film (100) may include both an amide repeating unit and an imide repeating unit.

[0072] According to one embodiment of the present invention, the imide repeating unit does not contain a perfluoroalkyl group. The imide repeating unit can be formed by the reaction of a diamine compound and a dianhydride compound.

[0073] According to one embodiment of the present invention, the amide repeating unit does not include a perfluoroalkyl group. The amide repeating unit can be formed by the reaction of a diamine compound and a dicarbonyl compound.

[0074] According to one embodiment of the present invention, monomer components may include a diamine compound and a dicarbonyl compound. When monomer components include a diamine compound and a dicarbonyl compound, the polyimide-based film (100) may have a polyamide polymer structure having amide repeating units.

[0075] According to one embodiment of the present invention, the monomer components may further include a dianhydride compound in addition to the diamine compound and the dicarbonyl compound. When the monomer components further include a dianhydride compound in addition to the diamine compound and the dicarbonyl compound, the polyimide-imide film (100) may have a polyamide-imide copolymer structure having both an imide repeating unit and an amide repeating unit.

[0076] According to one embodiment of the present invention, monomer components may include a diamine compound and a dianhydride compound. When monomer components include a diamine compound and a dianhydride compound, the polyimide film (100) may have a polyimide polymer structure having imide repeating units.

[0077] A film containing imide repeating units can be referred to as a polyimide-based film. Additionally, a film containing both amide repeating units and imide repeating units may also be referred to as a polyimide-based film. Hereinafter, to avoid confusion, a film containing both amide repeating units and imide repeating units will be referred to as a polyimide-based film.

[0078] A polyimide-based film (100) according to one embodiment of the present invention may include, for example, both an imide repeating unit and an amide repeating unit. Accordingly, a polyimide-based film (100) according to one embodiment of the present invention may have an amide-imide copolymer structure. The polyimide-based film (100) may be a polyamide film, a polyimide film, or a polyamide-imide film.

[0079] A polyimide-based film (100) according to one embodiment of the present invention does not contain perfluoroalkyl groups.

[0080] Perfluoroalkyl groups do not decompose easily due to their strong bonding force, so they can cause environmental pollution. A polyimide-based film (100) according to one embodiment of the present invention that does not contain perfluoroalkyl groups can be described as an eco-friendly film that can prevent environmental pollution.

[0081] The perfluoroalkyl group may include *-CF3 and *-CF2-*. Here, *- and -* are used to denote a bond or bonding position with another element, respectively.

[0082] A polyimide-based film (100) according to one embodiment of the present invention that does not contain perfluoroalkyl groups does not contain *-CF3 and *-CF2-*.

[0083] According to one embodiment of the present invention, the content of total organic fluorine (TOF) may be 50 ppm or less with respect to the total weight of the polyimide-based film. Here, organic fluorine may be an organic material containing a single bond of fluorine (F). A polyimide-based film (100) according to one embodiment of the present invention may contain 30 ppm or less of organic fluorine with respect to the total weight, may contain 10 ppm or less of organic fluorine, may contain 5 ppm or less of organic fluorine, may contain 1 ppm or less of organic fluorine, may contain 0.5 ppm or less of organic fluorine, and may contain 0.1 ppm or less of organic fluorine.

[0084] In addition, a polyimide-based film (100) according to one embodiment of the present invention may not contain fluorine (F). Assuming that a trace amount of fluorine (F) may be unexpectedly included during the manufacturing process of the polyimide-based film, the polyimide-based film (100) according to one embodiment of the present invention may have a fluorine concentration of less than 0.01 ppm.

[0085] According to one embodiment of the present invention, an amide repeating unit is formed by the reaction of a diamine compound and a dicarbonyl compound, wherein the diamine compound does not contain a perfluoroalkyl group. Accordingly, the diamine compound used in the preparation of the amide repeating unit does not contain *-CF3 and *-CF2-*.

[0086] According to one embodiment of the present invention, the diamine compound may include a cyclic structure within its chemical formula.

[0087] As a result of the inventors' research, it was confirmed that a polyimide-based film (100) manufactured using a diamine compound having a cyclic or semi-aromatic ring structure among cyclic structures has low heat resistance and relatively weak mechanical properties, making it difficult to use as a window film for a display device. In particular, when a cyclic diamine compound is used, it was confirmed that problems such as the generation of salt or a decrease in the degree of polymerization occur during the polymerization process, making mass production difficult.

[0088] Accordingly, the inventors designed a polyimide-based film (100) with the main chain having a structure that is as flat as possible, taking into account the problems that arise when using alicyclic raw materials.

[0089] Accordingly, a diamine compound according to one embodiment of the present invention may have an aromatic ring. For example, a diamine compound according to one embodiment of the present invention may include a compound represented by the following chemical formula 1.

[0090] [Chemical Formula 1]

[0091]

[0092] Here, R1 to R8 of Chemical Formula 1 may each include any one of hydrogen (H), methyl group (-CH3), ethyl group (-CH2CH3), bromine (Br), and chlorine (Cl).

[0093] The compound represented by Chemical Formula 1 can also be considered a benzidine-based diamine.

[0094] When a compound represented by Chemical Formula 1 is used as a diamine compound, the main chain of the polymer constituting the polyimide film (100) may have a flat structure.

[0095] Meanwhile, it was confirmed that when the diamine compound does not have substituents, the rate of stacking between molecules is high, resulting in a high probability of charge-transfer complex (CT-Complex) effects, and consequently, yellow color is expressed in the film.

[0096] Accordingly, according to one embodiment of the present invention, R1 to R8 included in the compound represented by Formula 1 may each include hydrogen (H), a methyl group (-CH3), and an ethyl group (-CH2CH3). Specifically, at least one of R1 to R4 of Formula 1 may include either a methyl group (-CH3) or an ethyl group (-CH2CH3), and at least one of R5 to R8 of Formula 1 may include either a methyl group (-CH3) or an ethyl group (-CH2CH3). More specifically, at least one of R1 to R4 of Formula 1 may include a methyl group (-CH3), and at least one of R5 to R8 of Formula 1 may include a methyl group (-CH3).

[0097] According to one embodiment of the present invention, the compound represented by Chemical Formula 1 may include at least one of the compound represented by Chemical Formula 2 (mTD), the compound represented by Chemical Formula 3 (oTD), and the compound represented by Chemical Formula 4 (TMB).

[0098] [Chemical Formula 2]

[0099]

[0100] [Chemical Formula 3]

[0101]

[0102] [Chemical Formula 4]

[0103]

[0104] According to one embodiment of the present invention, for example, any one of 2,2'-dimethylbenzidine (2,2'-Dimethylbenzidine, m-Tolidine) (mTD), 3,3'-dimethylbenzidine (3,3'-Dimethylbenzidine, o-Tolidine) (oTD) or 3,3',5,5'-tetramethylbenzidine (3,3',5,5'-Tetramethylbenzidine) (TMB) may be used as the diamine compound.

[0105] In addition, the diamine compound may include an atom or group of atoms with high electronegativity as a substituent. According to one embodiment of the present invention, the substituent may include an atom or group of atoms having an electronegativity of 2.7 or higher. Examples of atoms having an electronegativity of 2.7 or higher include chlorine (Cl), bromine (Br), etc.

[0106] According to one embodiment of the present invention, at least one of R1 to R8 included in the compound represented by Formula 1 may include either bromine (Br) or chlorine (Cl). More specifically, at least one of R1 to R4 of Formula 1 may include either bromine (Br) or chlorine (Cl), and at least one of R5 to R8 of Formula 1 may include either bromine (Br) or chlorine (Cl).

[0107] According to one embodiment of the present invention, the amide repeating unit does not contain a perfluoroalkyl group, and the dicarbonyl compound applied to the amide repeating unit also does not contain a perfluoroalkyl group. The dicarbonyl compound may not contain fluorine.

[0108] The dicarbonyl compound applied for the formation of the amide repeating unit may contain chlorine (Cl). For example, a dicarbonyl dichloride compound may be used as a dicarbonyl compound. The dicarbonyl compound may include aromatic dicarbonyl compounds and aliphatic dicarbonyl compounds.

[0109] According to one embodiment of the present invention, the dicarbonyl compound may have an aromatic ring.

[0110] Dicarbonyl dichloride compounds exhibit a high degree of polymerization with diamine compounds containing compounds represented by Chemical Formula 1, for example, benzidine-based diamines, and the polymer may have excellent mechanical properties. Dicarbonyl dichloride compounds may be compounds having a flat structure or compounds having a kink group.

[0111] According to one embodiment of the present invention, for example, 4,4'-Oxybis(benzoyl chloride) (DEDC) or isophthaloyl chloride (IPC) may be used as the dicarbonyl compound.

[0112] More specifically, the dicarbonyl compound may include at least one of the compound represented by the following chemical formula 5 (DEDC) and the compound represented by the following chemical formula 6 (IPC).

[0113] [Chemical Formula 5]

[0114]

[0115] [Chemical Formula 6]

[0116]

[0117] According to one embodiment of the present invention, an imide repeating unit is formed by the reaction of a diamine compound and a dianhydride compound, wherein the diamine compound and the dianhydride compound do not contain perfluoroalkyl groups. Accordingly, the diamine compound and the dianhydride compound used in the preparation of the imide repeating unit do not contain *-CF3 and *-CF2-*, respectively.

[0118] According to one embodiment of the present invention, the dianhydride compound is designed so that the main chain has a structure that is as flat as possible.

[0119] According to one embodiment of the present invention, the dianhydride compound may include a compound represented by the following chemical formula 7.

[0120] [Chemical Formula 7]

[0121]

[0122] Here, R9 to R12 of Chemical Formula 7 may each include any one of hydrogen (H), a methyl group (-CH3) and an ethyl group (-CH2CH3).

[0123] According to one embodiment of the present invention, a dianhydride compound may include a cyclic structure within its formula, such as the compound represented by Formula 7. The compound represented by Formula 7 may also be considered a cycloaliphatic dianhydride compound.

[0124] A cycloaliphatic dianhydride compound that does not significantly disturb the flat structure of the polymer main chain can be used. When a dianhydride compound that does not significantly disturb the flat structure of the polymer main chain is used, the optical properties of the polyimide film can be improved without degrading the mechanical properties of the polyimide film. For example, a polyimide film (100) prepared using a dianhydride compound containing a compound represented by Chemical Formula 7 can have improved light transmittance and improved yellowness.

[0125] According to one embodiment of the present invention, in the manufacture of a polyimide-based film (100), when a diamine compound comprising a compound represented by Formula 1 is used as the diamine compound, and a cycloaliphatic dianhydride compound that does not contain substituents is used as the reaction pair of the diamine compound, for example, a compound in which R9 to R12 of Formula 5 all contain hydrogen (H), the polyimide-based film (100) may have excellent mechanical properties. However, when a cycloaliphatic dianhydride compound that does not contain substituents is used as the reaction pair of the diamine compound, processability may be somewhat reduced.

[0126] According to one embodiment of the present invention, in the manufacture of a polyimide-based film (100), when a diamine compound comprising a compound represented by Formula 1 is used as the diamine compound, and a cycloaliphatic dianhydride compound comprising a substituent is used as the reaction pair of the diamine compound, for example, a compound in which at least one of R9 to R12 of Formula 5 comprises either a methyl group (-CH3) or an ethyl group (-CH2CH3), the polyimide-based film (100) is manufactured, and the mechanical properties are the same or similar compared to the case where a cycloaliphatic dianhydride compound not comprising a substituent is used, and the processability can be improved.

[0127] According to one embodiment of the present invention, the dianhydride compound may include at least one of the compounds represented by the following chemical formulas 8 to 12.

[0128] [Chemical Formula 8]

[0129]

[0130] [Chemical Formula 9]

[0131]

[0132] [Chemical Formula 10]

[0133]

[0134] [Chemical Formula 11]

[0135]

[0136] [Chemical Formula 12]

[0137]

[0138] According to one embodiment of the present invention, in order for the polyimide-based film (100) to have excellent mechanical properties and processability, a cycloaliphatic dianhydride compound having a substituent as a dianhydride compound and a cycloaliphatic dianhydride compound not having a substituent may be used together.

[0139] According to one embodiment of the present invention, the imide repeating unit does not contain a perfluoroalkyl group, and the dianhydride compound applied to the imide repeating unit also does not contain a perfluoroalkyl group. The dianhydride compound may not contain fluorine.

[0140] According to one embodiment of the present invention, when a polyimide-based film (100) includes an amide repeating unit, the molar ratio of a dicarbonyl compound and a dianhydride compound is adjusted to a predetermined range so that the solubility of the resin does not change significantly even during a chemical imidization process.

[0141] A polyimide-based film (100) according to one embodiment of the present invention may include 10% or more of amide repeating units based on the total number of repeating units.

[0142] To this end, the monomer for manufacturing a polyimide-based film can be adjusted so that the content of the dicarbonyl compound is 10 mol% or more with respect to the total content of the dicarbonyl compound and the dianhydride compound on a molar basis.

[0143] More specifically, with respect to the total number of moles of the dicarbonyl compound and the dianhydride compound, the dicarbonyl compound may have a content in the range of 10 mole% to 100 mole%, and the dianhydride compound may have a content in the range of 0 mole% to 90 mole%.

[0144] A polyimide-based film (100) according to one embodiment of the present invention may further include additives. For example, at least one of an antioxidant, a UV stabilizer, a UV absorber, microparticles, nanoparticles, a light stabilizer, a polymerization initiator, a leveling agent, and a bluening agent may be used.

[0145] Phenol-based primary antioxidants and phosphorus-based secondary antioxidants can be used as antioxidants.

[0146] Hindered amine light stabilizers (HALS) can be used as UV stabilizers.

[0147] As a UV absorber, at least one of a UV A (UVA) absorber that absorbs ultraviolet rays with a wavelength of 320 nm to 400 nm and a UV B (UVB) absorber that absorbs ultraviolet rays with a wavelength of 290 nm to 320 nm may be used.

[0148] In order to improve the light transmittance or friction coefficient of a polyimide-based film (100), microparticles having a particle size in the micrometer range or nanoparticles having a particle size in the nanometer range may be used. For example, silicon oxide, metal oxide, etc. may be used as microparticles or nanoparticles.

[0149] A bluing agent may be used to improve the yellowness of the polyimide-based film (100). The bluing agent may absorb yellow light. A dye-type bluing agent or a pigment-type bluing agent may be used.

[0150] A polyimide-based film (100) according to one embodiment of the present invention may have a yellowness of 8.0 or less based on a thickness of 50 μm.

[0151] According to one embodiment of the present invention, the polyimide-based film (100) includes a diamine compound and a dianhydride compound containing substituents, so that the stacking phenomenon between molecules or polymer chains is less likely to occur and the polymer main chains can have an asymmetric structure, so that it can have a low yellowness even without including perfluoroalkyl groups.

[0152] The yellowness of the polyimide film (100) can be measured by a spectrophotometer according to the standard ASTM E313. For example, a KONICA MINOLTA CM-3700D can be used as a spectrophotometer.

[0153] If the yellowness (YI) of the polyimide film (100) exceeds 8.0, the polyimide film (100) may have an excessively yellow tint and may lack visibility, making it difficult to apply to a display device.

[0154] A polyimide-based film (100) according to one embodiment of the present invention may have a light transmittance of 85% or more at a wavelength of 380 to 780 nm.

[0155] The light transmittance of the polyimide-based film (100) can be obtained by measuring the average light transmittance in the wavelength range of 380 to 780 nm using a spectrophotometer according to the standard ASTM E313. For example, the CM-3700D from KONICA MINOLTA can be used as the spectrophotometer.

[0156] If the light transmittance of the polyimide film (100) is less than 85%, it may be difficult to apply it to a display device due to insufficient visibility.

[0157] A polyimide-based film (100) according to one embodiment of the present invention may have a haze of 0.8% or less based on a thickness of 50 μm.

[0158] The haze of the polyimide film (100) can be measured by a haze meter according to the standard ASTM D1003. For example, the HM-150 from MURAKAMI can be used as the haze meter.

[0159] If the haze of the polyimide film (100) exceeds 0.8%, it may be difficult to apply it to a display device due to insufficient visibility.

[0160] A polyimide-based film (100) according to one embodiment of the present invention may have a modulus (Young's modulus) of 4.0 GPa or more based on a thickness of 50 μm.

[0161] The modulus of the polyimide film (100) can be measured using a universal tensile testing machine according to the standard ASTM D885. For example, the MODEL 5967 from Instron can be used as the universal tensile testing machine.

[0162] If the modulus of the polyimide film (100) is less than 4.0 GPa, deformation due to external force may occur.

[0163] A polyimide-based film (100) according to one embodiment of the present invention may have an elongation of 10% or more based on a thickness of 50 μm.

[0164] The elongation at break of the polyimide film (100) can be measured using a universal tensile testing machine according to the standard ASTM D885. For example, the MODEL 5967 from Instron can be used as the universal tensile testing machine.

[0165] If the elongation at break of the polyimide-based film (100) is less than 10%, it may have low folding performance due to low stress absorption ability, making it difficult to apply to a foldable display device.

[0166] A polyimide-based film (100) according to one embodiment of the present invention may have a thickness sufficient to protect a display panel. For example, the polyimide-based film (100) may have a thickness of 10 to 100 μm. More specifically, the polyimide-based film (100) may have a thickness of 30 to 80 μm, a thickness of 40 to 60 μm, or a thickness of 50 μm.

[0167] Hereinafter, with reference to FIGS. 1 and FIGS. 2, a display device (200) using a polyimide-based film (100) according to one embodiment of the present invention will be described.

[0168] FIG. 1 is a cross-sectional view of a part of a display device (200) according to another embodiment of the present invention, and FIG. 2 is an enlarged cross-sectional view of the "P" portion of FIG. 1.

[0169] Referring to FIG. 1, a display device (200) according to another embodiment of the present invention includes a display panel (501) and a polyimide-based film (100) on the display panel (501).

[0170] Referring to FIGS. 1 and 2, a display panel (501) comprises a substrate (510), a thin-film transistor (TFT) on the substrate (510), and an organic light-emitting element (570) connected to the thin-film transistor (TFT). The organic light-emitting element (570) comprises a first electrode (571), an organic light-emitting layer (572) on the first electrode (571), and a second electrode (573) on the organic light-emitting layer (572). The display device (200) disclosed in FIGS. 1 and 2 is an organic light-emitting display device.

[0171] The substrate (510) may be made of glass or plastic. Specifically, the substrate (510) may be made of plastic such as polyimide resin. Although not illustrated, a buffer layer may be placed on the substrate (510).

[0172] A thin-film transistor (TFT) is placed on a substrate (510). The thin-film transistor (TFT) includes a semiconductor layer (520), a gate electrode (530) that is insulated from the semiconductor layer (520) and overlaps with at least a portion of the semiconductor layer (520), a source electrode (541) connected to the semiconductor layer (520), and a drain electrode (542) that is spaced apart from the source electrode (541) and connected to the semiconductor layer (520).

[0173] Referring to FIG. 2, a gate insulating film (535) is disposed between the gate electrode (530) and the semiconductor layer (520). An interlayer insulating film (551) is disposed on the gate electrode (530), and a source electrode (541) and a source electrode (541) can be disposed on the interlayer insulating film (551).

[0174] A flattening film (552) is placed on a thin film transistor (TFT) to flatten the top of the thin film transistor (TFT).

[0175] The first electrode (571) is placed on the planarization film (552). The first electrode (571) is connected to a thin-film transistor (TFT) through a contact hole provided in the planarization film (552).

[0176] The bank layer (580) is disposed on a part of the first electrode (571) and on the planarization film (552) to define a pixel area or a light-emitting area. For example, the bank layer (580) may be disposed in a matrix structure in the boundary area between a plurality of pixels, so that the pixel area can be defined by the bank layer (580).

[0177] The organic light-emitting layer (572) is disposed on the first electrode (571). The organic light-emitting layer (572) may also be disposed on the bank layer (580). The organic light-emitting layer (572) may include a single light-emitting layer or two or more light-emitting layers stacked vertically. Light having any one of red, green, and blue colors may be emitted from the organic light-emitting layer (572), and white light may also be emitted.

[0178] The second electrode (573) is placed on the organic light-emitting layer (572).

[0179] An organic light-emitting device (570) can be formed by stacking a first electrode (571), an organic light-emitting layer (572), and a second electrode (573).

[0180] Although not illustrated, when the organic light-emitting layer (572) emits white light, individual pixels may include a color filter for filtering the white light emitted from the organic light-emitting layer (572) by wavelength. The color filter is formed on the path of the light.

[0181] 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 film and at least one inorganic film, and at least one organic film and at least one inorganic film may be disposed alternately.

[0182] A polyimide-based film (100) is placed on a display panel (501) having the laminated structure described above.

[0183] Hereinafter, a method for manufacturing a polyimide-based film (100) according to one embodiment of the present invention will be described in detail.

[0184] A method for manufacturing a polyimide-based film (100) according to one embodiment of the present invention comprises the steps of: preparing a liquid resin composition using monomer components including a diamine compound and a dicarbonyl compound; molding the liquid resin composition to produce a gel-state film; and drying the gel-state film.

[0185] To manufacture a polyimide-based film (100), first, monomer components including a diamine compound and a dicarbonyl compound are polymerized. The monomer components may further include a dianhydride compound.

[0186] When monomer components include a diamine compound, a dianhydride compound, and a dicarbonyl compound, the diamine compound and the dianhydride compound may be polymerized first, and then the diamine compound and the dicarbonyl compound may be polymerized.

[0187] A first solvent may be used for the solution polymerization of monomer components. Specifically, monomer components may be reacted in the presence of the first solvent to prepare a first polymer solution. An organic solvent may be used as the first solvent for solution polymerization.

[0188] There are no specific restrictions on the type of the first solvent. As the first solvent, for example, at least one solvent selected from m-cresol, N-methyl-2-pyrrolidone (NMP), N-ethyl-2-pyrrolidone (NEP), dimethylformamide (DMF), diethylformamide (DEF), dimethylacetamide (DMAc), diethylacetamide (DEAc), acetone, ethyl acetate, propylene glycol monomethyl ether (PGME), and propylene glycol monomethyl ether acetate (PGME). In addition, low-boiling point solvents such as tetrahydrofuran (THF) and chloroform, or low-absorbency solvents such as γ-butyrolactone, may be used as the first solvent. Depending on the purpose, the first solvent may be used alone or as a mixture of two or more types.

[0189] There is no special limitation on the content of the first solvent. The first solvent may have a content of 50 to 95 weight percent relative to the total weight of the first polymer solution. The first solvent may also have a content of 70 to 90 weight percent relative to the total weight of the first polymer solution.

[0190] The first polymer solution may include a polyamic acid solution. In this case, there are no special restrictions on the reaction conditions. The reaction temperature may be adjusted, for example, to a range of -10 to 80°C, and the reaction time may be adjusted to 2 to 48 hours. The step of preparing the first polymer solution may be carried out in an inert gas atmosphere such as argon or nitrogen.

[0191] Next, an imidization process for the first polymer solution may be carried out. At this time, the polyamic acid contained in the first polymer solution may be imidized.

[0192] For imidation, thermal imidation, chemical imidation, or a combination of thermal imidation and chemical imidation may be applied.

[0193] According to one embodiment of the present invention, a chemical imidation method may be applied. The chemical imidation method is a method of applying a dehydrating agent, such as acetic anhydride, and an imidation catalyst, such as isoquinoline, β-picoline, pyridine, or tertiary amine, to a first polymer solution.

[0194] Chemical imidation may be combined with thermal imidation.

[0195] When the thermal imidation method and the chemical imidation method are used in combination, a dehydrating agent and an imidation catalyst are added to the first polymer solution and heated at 20 to 180°C for 1 to 12 hours to proceed with imidation.

[0196] Next, a second solvent is added to the first polymer solution, and the solution is filtered and dried to produce a polymer solid.

[0197] The second solvent is used to obtain a solid component of the polyimide-based resin. Accordingly, a solvent that does not dissolve the polyamic acid contained in the first polymer solution may be used as the second solvent, and a solid component of the polyimide-based polymer may be precipitated due to the difference in solubility. A solvent with lower polarity than the first solvent may be used as the second solvent. As the second solvent, for example, one or more selected from water, alcohols, ethers, and ketones may be used.

[0198] There is no special limitation on the content of the second solvent. A second solvent may be used in an amount of 5 to 20 times the weight of the polyamic acid contained in the first polymer solution.

[0199] The conditions for filtering and drying the obtained polymer solid are determined by considering the boiling points of the second solvent and the first solvent remaining in the polymer solid. For example, the polymer solid can be dried at a temperature of 50 to 150°C for 2 to 24 hours.

[0200] Next, the polymer solid is dissolved in a third solvent to prepare a liquid resin composition. The liquid resin composition may also be referred to as a polyimide-based resin composition.

[0201] According to one embodiment of the present invention, the third solvent may be the same as the first solvent. Accordingly, as the third solvent, for example, at least one selected from m-cresol, N-methyl-2-pyrrolidone (NMP), N-ethyl-2-pyrrolidone (NEP), dimethylformamide (DMF), diethylformamide (DEF), dimethylacetamide (DMAc), diethylacetamide (DEAc), acetone, ethyl acetate, propylene glycol monomethyl ether (PGME), and propylene glycol monomethyl ether acetate (PGME) may be used.

[0202] The liquid resin composition prepared in this manner may have a viscosity of 100 to 300,000 cPs. If the viscosity of the liquid resin composition is less than 100 cPs, it may be difficult to form the liquid resin composition into a film by casting, and due to the low molecular weight, it may be difficult to peel the film formed by casting from the casting substrate. On the other hand, if the viscosity of the liquid resin composition exceeds 300,000 cPs, the pressure applied during the casting process increases due to the high viscosity, which may be disadvantageous in terms of the process.

[0203] More specifically, the liquid resin composition may have a viscosity of 1,000 to 250,000 cPs. When the liquid resin composition has a viscosity of 1,000 to 250,000 cPs, it is easy to cast the liquid resin composition to form a film, and drying is also easy. For example, when the viscosity of the liquid resin composition is 1,000 cPs or higher, there is no difficulty in casting the liquid resin composition to form a film, and the film formed by casting can be peeled off from the casting substrate without difficulty. In addition, when the viscosity of the liquid resin composition is 250,000 cPs or lower, the casting process can proceed without the pressure for casting the liquid resin composition increasing more than necessary.

[0204] According to one embodiment of the present invention, the liquid resin composition may have a viscosity of 1,000 to 30,000 cPs.

[0205] According to one embodiment of the present invention, the content of solids included in the liquid resin composition can be adjusted to a range of 5 to 30 weight percent with respect to the total weight of the liquid resin composition.

[0206] Next, a gel-state film is prepared using a liquid resin composition. The gel-state film may be referred to as an uncured polyimide-based film. According to one embodiment of the present invention, a gel-state film refers to a film in a state where curing has not been completed. Even if partial curing has occurred, if the curing is not completed, it is referred to as a gel-state film or an uncured polyimide-based film.

[0207] A casting method may be applied to manufacture a gel-state film. Specifically, the step of manufacturing a gel-state film includes the step of casting a liquid resin composition onto a support.

[0208] There are no special restrictions on the casting method, and casting methods known in the art may be applied. A gel-state film is produced by casting.

[0209] Glass plates, aluminum substrates, circulating stainless steel belts, stainless steel drums, or heat-resistant polymer films can be used as supports.

[0210] Next, the gel-state film can be dried and heat-treated to produce a polyimide-based film (100).

[0211] Drying can be performed, for example, in a temperature range of 50 to 150°C. Drying may include primary drying and secondary drying.

[0212] Heat treatment may be performed on the gel-state film after drying. A known thermosetting process may be applied as the heat treatment. For example, the gel-state film may be heat-treated at a temperature of 100 to 500°C for 1 minute to 1 hour. Through this heat treatment, the gel-state film is thermosetting to complete a polyimide-based film. The heat treatment step is also referred to as the thermosetting step.

[0213] The heat treatment step may be performed on a support or on a separate heat treatment support. For example, after drying, the gel-state film may be separated from the support, fixed to a support for heat treatment, and then the heat treatment may proceed.

[0214] According to one embodiment of the present invention, heat treatment may be performed while a constant tension is applied to a polyimide-based film. Residual stress inside the polyimide-based film can be removed by the heat treatment.

[0215] Drying and heat treatment may be performed simultaneously.

[0216] The present invention will be described in more detail below with reference to specific embodiments. However, the scope of the present invention is not limited by the following embodiments.

[0217] <Example 1>

[0218] 359.126 g of DMAc (N,N-Dimethylacetamide) is filled into a 500 ml reactor equipped with a stirrer, nitrogen injection device, dropping funnel, temperature controller, and cooler while passing nitrogen through it. After setting the reactor temperature to 25°C, 14.861 g (0.07 mol) of m-Tolidine is dissolved, and the solution is maintained at 25°C. After lowering the reactor temperature to below 10°C, 17.352 g of PO (Propylene oxide) is added. Once it is determined that the solution is evenly stirred, 20.658 g (0.07 mol) of DEDC is added, followed by stirring at a low temperature for about 30 minutes, and then slowly raising the temperature to room temperature. When the reactor temperature is set back to 25°C, the reaction is carried out for more than 12 hours to obtain a polymer solution with a solid content concentration of 9 wt%.

[0219] The obtained polymer solution is rapidly stirred while slowly adding approximately 2.2 L of methanol to facilitate the reprecipitation of the solids. The solution after reprecipitation is complete is called the reprecipitate. This reprecipitate is poured into a Buchner funnel-type vacuum system (using filter paper) to begin filtration. As methanol and DMAc are primarily removed from the reprecipitate through the Buchner funnel, only the polymer solids remain; subsequently, approximately 1.4 L of methanol is poured over them to obtain a purer solid through a washing process. To remove as much residual solvent from the obtained solids as possible, they are dried under vacuum at approximately 100°C for at least 6 hours, resulting in a polyimide-based polymer solid suitable for redissolution in an appropriate organic solvent.

[0220] Redissolution using an organic solvent is carried out to form a film of the obtained polymer solid.

[0221] After filling a 500ml reactor with 225g of DMAc and maintaining the reactor temperature at 25℃, 25g of the previously obtained polymer solids is added to the reactor. Then, wait until completely dissolved.

[0222] The obtained redissolved solution was subsequently cast. A casting substrate is used for casting. There are no specific restrictions on the type of casting substrate. Glass substrates, stainless steel (SUS) substrates, Teflon substrates, etc., may be used as casting substrates. According to one embodiment of the present invention, a glass substrate may be used as the casting substrate.

[0223] After casting at room temperature, the film was prepared by placing it in a hot air oven set to a temperature of 80°C and slowly drying it to 120°C at a speed of 3.5°C / min for about 11 to 12 minutes, and the prepared film was peeled off from a glass substrate and fixed to a frame with a pin.

[0224] The frame with the fixed film was placed in a hot air oven and slowly heated from 120°C to 230°C for about 40 minutes, then slowly cooled and separated from the frame to obtain the optical film. The optical film was then heat-treated at 200°C for 1 minute.

[0225] As a result, an optical film with a thickness of about 50㎛ was completed.

[0226] <Example 2>

[0227] 352.120 g of DMAc (N,N-Dimethylacetamide) was added to a 500 ml reactor equipped with a stirrer, nitrogen injector, dropping funnel, temperature controller, and cooler while passing nitrogen through it. After setting the reactor temperature to 25°C, 14.861 g (0.07 mol) of m-Tolidine was dissolved, and the solution was maintained at 25°C. 1.373 g (0.007 mol) of CBDA was added to this solution, and the mixture was stirred for 3 hours to completely dissolve the CBDA. After lowering the reactor temperature to below 10°C, 26.028 g of PO (Propylene Oxide) was added. Once it was determined that the solution was evenly stirred, 18.593 g (0.063 mol) of DEDC was added, followed by stirring at a low temperature for about 30 minutes, and then slowly raising the temperature to room temperature. When the temperature of the reactor is adjusted back to 25℃, the reaction is carried out for more than 12 hours to obtain a polymer solution with a solid content concentration of 9% by weight.

[0228] 1.22 g of pyridine and 1.57 g of acetic anhydride are added to the obtained polymer solution and stirred for 30 minutes, after which the temperature of the polymer solution is raised to 80°C. Once the temperature of the polymer solution reaches 80°C, chemical imidation is carried out by stirring at the same temperature for 1 hour, and after completion, the polymer solution is cooled back to room temperature.

[0229] Below, an optical film with a thickness of about 50 μm was manufactured using the same method as in Example 1.

[0230] <Examples 3 to 17>

[0231] Using the monomers disclosed in Table 1 below, an optical film was prepared in the same manner as in Example 2, according to the composition and content disclosed in Table 1. The content disclosed in Table 1 represents the relative content based on the moles, where the total moles of the diamine compound are set to 100.

[0232] The optical films prepared in Examples 1 to 17 can be described as polyimide-based films.

[0233] <Comparative Example 1>

[0234] 289.064 g of DMAc(N,N-Dimethylacetamide) was filled into a 500 ml reactor equipped with a stirrer, nitrogen injector, dropping funnel, temperature controller, and cooler while passing nitrogen through it. After setting the reactor temperature to 25°C, 14.861 g (0.07 mol) of m-Tolidine was dissolved, and the solution was maintained at 25°C. 13.728 g (0.07 mol) of CBDA was added to this solution and stirred for 3 hours to completely dissolve the CBDA. The reactor temperature was fixed at 25°C, and the reaction was carried out for at least 12 hours to obtain a polymer solution.

[0235] Below, an optical film with a thickness of about 50 μm was prepared using the same method as in Example 2.

[0236] The optical film manufactured in Comparative Example 1 can be described as a polyimide-based film.

[0237] <Comparative Examples 2 to 5>

[0238] An optical film was prepared in the same manner as in Example 2 using the monomer disclosed in Table 1 below, according to the content disclosed in Table 1. The content disclosed in Table 1 represents the relative content based on the moles, where the total moles of the diamine compound are set to 100.

[0239] The optical films prepared in Comparative Examples 2 to 5 can be described as polyimide-based films.

[0240] Classification Diamine Compounds Dianhydride Compounds Dicarbonyl Compounds mTDoTDTMBTFDB44ODAtCHDCBDADMCBDADEDCIPC Example 1 100-----0-100- Example 2 100-----10-90- Example 3 100-----20-80- Example 4 100-----40-60- Example 5 100-----50-50- Example 6 100-----80-20- Example 7 100-----90-10- Example 8 100---- -10--90 Example 9 100-----40--60 Example 10 100-----90-10 Example 11-100----40-60-Example 12--100---40-60-Example 13 100------2080-Example 14 100------4060-Example 15 100------8020-Example 16 100------90-10 Example 17-100-----4060-Comparative Example 11 00-----100--Comparative Example 2 100-----955-Comparative Example 3---100--5050-Comparative Example 4----100-5050-Comparative Example 5-----1005050-

[0241] [Diamine Compounds]

[0242] mTD: m-Tolidine, 2,2'-Dimethylbenzidine

[0243] oTD: o-Tolidine, 3,3'-Dimethylbenzidine

[0244] TMB: 3,3',5,5'-Tetramethylbenzidine

[0245] TFDB: 2,2'-Bis(trifluoromethyl)benzidine

[0246] 44ODA: 4,4′-Oxydianiline

[0247] tCHD: 1,4-Cyclohexane diamine

[0248] [Dianhydride compounds]

[0249] DMCBDA: 1,3-Dimethyl-Cyclobutane-1,2,3,4-Tetracarboxylic Dianhydride

[0250] CBDA: Cyclobutane-1,2,3,4-tetracarboxylic dianhydride

[0251] [Dicarbonyl Compounds]

[0252] DEDC: 4,4'-Oxybis(benzoyl chloride)

[0253] IPC: Isophthaloyl Chloride

[0254] Methods for Measuring Physical Properties

[0255] The physical properties of the optical films prepared in Examples 1 to 17 and Comparative Examples 1 to 5 were measured by the following method, and the results are disclosed in Table 2.

[0256] (1) Fluorine detection

[0257] A combustion method was applied to optical films prepared according to Examples 1 to 17 and Comparative Examples 1 to 5 to check for the detection of fluorine.

[0258] Specifically, according to the "BS EN 14582:2016 standard," the optical film specimens were burned and the presence of fluorine was confirmed by the ion chromatography (IC) method. An IC (Ion Chromatography) device was used to confirm the presence of fluorine.

[0259] (2) Yellow Index (YI)

[0260] The yellowness of the polyimide-based films prepared according to Examples 1 to 17 and Comparative Examples 1 to 5 was measured using a spectrophotometer (KONICA MINOLTA CM-3700D) in accordance with ASTM E313.

[0261] (3) Light transmittance (TT)

[0262] For the polyimide-based films prepared according to Examples 1 to 17 and Comparative Examples 1 to 5, the average light transmittance was measured in the wavelength range of 380 to 780 nm using a spectrophotometer (CM-3700D of KONICA MINOLTA).

[0263] (4) Hayes

[0264] The haze of the polyimide-based films prepared according to Examples 1 to 17 and Comparative Examples 1 to 5 was measured using a haze meter (HM-150 of MURAKAMI).

[0265] (5) Measurement of modulus and elongation at break

[0266] Young's modulus and elongation at break of polyimide-based films prepared according to Examples 1 to 17 and Comparative Examples 1 to 5 were measured using a universal tensile testing machine (Model 5967 of Instron) according to the ASTM D885 method.

[0267] The measurement results are as shown in Table 2 below.

[0268] Classification Film Formation Status Fluorine Detection YITT (%) Haze (%) Modulus (GPa) Elongation at Break (%) Example 1 OX 6.8 8 7.0 0.3 4.3 45 Example 2 OX 6.6 8 6.8 0.2 4.4 44 Example 3 OX 6.2 8 7.0 0.3 5.1 44 Example 4 OX 5.4 8 6.6 0.2 5.8 42 Example 5 OX 4.9 8 7.1 0.4 6.7 38 Example 6 OX 3.2 8 7.4 0.4 7.6 13 Example 7 OX 3.3 8 7.5 0.6 7.8 11 Example 8 OX 7.7 8 6.5 0.3 4.1 32 Example 9 OX 6.3 8 6.4 0.6 5.6 23 Example 10 OX 4.1 8 7.0 0.6 7.7 12 Example 11OX5.486.60.35.628 Example 12OX4.987.10.35.322 Example 13OX5.987.10.35.039 Example 14OX5.286.60.35.840 Example 15OX3.187.50.37.515 Example 16OX4.187.00.67.713 Example 17OX5.286.80.25.430 Comparative Example 1X------Comparative Example 2OX3.287.21.17.83 Comparative Example 3OO1.889.60.26.833 Comparative Example 4OX13.284.40.34.247 Comparative Example 5X------

[0269] According to Table 2 above, it can be confirmed that Examples 1 to 17 do not contain fluorine, have excellent optical properties with a yellowness of 8.0 or less, a light transmittance of 85% or more, and a haze of 0.8 or less, and have excellent mechanical properties with a modulus of 4.0 GPa or more and an elongation at break of 10% or more.

[0270] On the other hand, Comparative Examples 1 and 5 could not be formed into films, so their physical properties could not be measured. Comparative Example 2 had an elongation at break of less than 10, confirming that its mechanical properties were insufficient. Comparative Example 3 had excellent optical and mechanical properties, but it was confirmed that fluorine was detected. Comparative Example 4 had a yellowness greater than 8.0 and a light transmittance of less than 85%, confirming that its optical properties were insufficient.

[0271] [Explanation of the symbol]

[0272] 100: Polyimide-based film

[0273] 200: Display device

[0274] 501: Display panel

Claims

1. Includes at least one of an imide repeating unit and an amide repeating unit, The above imide repeating unit is formed by the reaction of a diamine compound and a dianhydride compound, and The above amide repeating unit is formed by the reaction of a diamine compound and a dicarbonyl compound, and The above diamine compound comprises a polyimide-based film comprising a compound represented by the following chemical formula 1: [Chemical Formula 1] Here, R1 to R8 of the above chemical formula 1 each include at least one of hydrogen (H), a methyl group (-CH3), and an ethyl group (-CH2CH3).

2. In Paragraph 1, A polyimide-based film in which each of the above imide repeating unit and amide repeating unit does not contain a perfluoroalkyl group.

3. In Paragraph 2, The above perfluoroalkyl group comprises *-CF3 and *-CF2-, in a polyimide-based film: Here, *- and -* each mean combining with other elements.

4. In Paragraph 1, A polyimide-based film in which at least one of R1 to R8 of the above chemical formula 1 comprises a methyl group.

5. In Paragraph 1, At least one of R1 to R4 of the above chemical formula 1 comprises a methyl group, and A polyimide-based film in which at least one of R5 to R8 of the above chemical formula 1 comprises a methyl group.

6. In Paragraph 1, A polyimide-based film comprising at least one of the compounds represented by the following chemical formulas 2 to 4, wherein the compound represented by the above chemical formula 1. [Chemical Formula 2] [Chemical Formula 3] [Chemical Formula 4] 7. In Paragraph 1, The above dicarbonyl compound is a polyimide-based film having an aromatic ring.

8. In Paragraph 1, The above dicarbonyl compound is a polyimide-based film having a rotatable group.

9. In Paragraph 1, A polyimide-based film comprising at least one of the dicarbonyl compound represented by the following chemical formula 5 and the compound represented by the following chemical formula 6. [Chemical Formula 5] [Chemical Formula 6] 10. In Paragraph 1, The above dianhydride compound comprises a polyimide-based film comprising a compound represented by the following chemical formula 7: [Chemical Formula 7] Here, R9 to R12 of the above chemical formula 7 each include at least one of hydrogen (H), a methyl group (-CH3), and an ethyl group (-CH2CH3).

11. In Paragraph 10, A polyimide-based film in which at least one of R9 to R12 of the above chemical formula 7 comprises a methyl group.

12. In Paragraph 10, A polyimide-based film comprising at least one of the compounds represented by the following chemical formulas 8 to 12, wherein the compound represented by the above chemical formula 7. [Chemical Formula 8] [Chemical Formula 9] [Chemical Formula 10] [Chemical Formula 11] [Chemical Formula 12] 13. In Paragraph 1, A polyimide-based film in which, based on the molar amount, the content of the dicarbonyl compound is 10 mol% or more relative to the total content of the dicarbonyl compound and the dianhydride compound.

14. In Paragraph 1, A polyimide-based film having a yellowness of 8.0 or less based on a thickness of 50㎛.

15. In Paragraph 1, A polyimide-based film having a light transmittance of 85% or more at a wavelength of 380 to 780 nm.

16. In Paragraph 1, A polyimide-based film having a haze of 0.8 or less based on a thickness of 50㎛.

17. In Paragraph 1, A polyimide-based film having a modulus (Young's modulus) of 4.0 GPa or more based on a thickness of 50 µm.

18. In Paragraph 1, A polyimide-based film having an elongation at break of 10% or more based on a thickness of 50㎛.

Images