WO2021101077A1

WO2021101077A1 - Polyimide film and manufacturing method therefor

Info

Publication number: WO2021101077A1
Application number: PCT/KR2020/014234
Authority: WO
Inventors: 원동영; 박세주; 김동영
Original assignee: 피아이첨단소재 주식회사
Priority date: 2019-11-21
Filing date: 2020-10-19
Publication date: 2021-05-27
Also published as: KR102347593B1; JP2023503090A; TWI762040B; KR20210062283A; CN114729140A; TW202124532A; CN114729140B

Abstract

Disclosed are a polyimide film and a manufacturing method therefor, the polyimide film being derived from the imidization of a polyamic acid formed from the reaction of a dianhydride monomer and a diamine monomer, wherein the dianhydride monomer comprises approximately 10-90 mol% of biphenyltetracarboxylic dianhydride (BPDA) on the basis of the total number of moles of the dianhydride monomer, and the polyimide film satisfies the following relation 1 and has a modulus of approximately 2-4.5 GPa. <Relation 1> approximately 21 MPa/% ≤ A/B ≤ approximately 30 MPa/%, and in relation 1, A is the yield strength of a polyimide film in units of MPa, and B is the yield point of the polyimide film in units of %.

Description

Polyimide film and its manufacturing method

It relates to a polyimide film and a method for producing the same. More specifically, it relates to a polyimide film having a high yield point at a low modulus of elasticity and less damage to repeated deformation, and a method of manufacturing the same.

Flexible displays, such as curved, bendable, foldable, and rollable, are the next generation displays that have recently attracted attention from both academia and industry. Among the various types of materials constituting a flexible display, functional film/coating material is an important polymer substrate material constituting a flexible display, and it can be said to be a key material essential for the successful implementation and development of a flexible display. It is attracting attention.

Polyimide is a polymer characterized by having a heteroimide ring in its main chain, and has excellent mechanical properties, flame retardancy, chemical resistance, and low dielectric constant, in addition to excellent heat resistance, and has been applied to a wide range of applications such as coating materials, molding materials, and composite materials.

The most important physical property required for a flexible display polymer substrate is flexibility. In particular, such a polymer substrate should not be damaged during the curving, bending, folding, rolling, and stretching processes in which the flexible display repeatedly deforms, and various initial physical properties should not be lost.

It is an object of the present invention to provide a polyimide film having a high yield point at a low modulus of elasticity and less damage even in repeated deformation.

Another object of the present invention is to provide a method for producing the above-described polyimide film.

1. According to one aspect, it is a polyimide film derived from imidization of a polyamic acid formed from the reaction of a dianhydride monomer and a diamine monomer, and the dianhydride monomer is biphenyltetracarboxylic acid dianhydride (BPDA), and the total molar amount of the dianhydride monomer Based on about 10 mol% to about 90 mol%, the polyimide film satisfies Equation 1 below, and a polyimide film having a modulus of about 2 GPa to about 4.5 GPa is provided:

Approx. 21 MPa/% ≤ A/B ≤ Approx. 30 MPa/%

In Formula 1, A is the yield strength of the polyimide film, the unit is MPa, and B is the yield point of the polyimide film, and the unit is %.

2. In the first embodiment, the dianhydride monomer may further include pyromellitic dianhydride (PMDA).

3. In the second embodiment, the pyromellitic dianhydride may be included in an amount of about 10 mol% to about 90 mol% based on the total molar amount of dianhydride monomers.

4. In any one of the first to third embodiments, the diamine monomer is m-tolidine (m-TD), 4,4'-oxydianiline (ODA), 1,3-bis(4-amino). Phenoxy)benzene (TPE-R), 2,2-bis(4-[4-aminophenoxy]-phenyl)propane (PAPP), or combinations thereof.

5. In the fourth embodiment, the diamine monomer may include m-tolidine (m-TD) and 4,4'-oxydianiline (ODA) in a molar ratio of about 1:99 to about 20:80. have.

6. In any one of the first to fifth embodiments, the polyimide film may have a yield strength of about 50 Mpa to about 80 MPa.

7. In any one of the first to sixth embodiments, the polyimide film may have a yield point of about 2.2% to about 2.9%.

8. According to another aspect, it is a method of manufacturing a polyimide film according to any one of the first to seventh embodiments, wherein the method is to form a polyamic acid solution by mixing and reacting a dianhydride monomer, a diamine monomer, and an organic solvent, ; Mixing the polyamic acid solution with a dehydrating agent and an imidizing agent to form a polyimide precursor composition; Casting the polyimide precursor composition on a support and drying to prepare a gel film; And, by heat-treating the gel film to form a polyimide film; It may include steps.

9. In the eighth embodiment, the heat treatment may be performed at about 100° C. to about 700° C.

The polyimide film and its manufacturing method of the present invention may have an effect of providing a polyimide film having a high yield point at a low elastic modulus.

In describing the present invention, when it is determined that a detailed description of a related known technology may unnecessarily obscure the subject matter of the present invention, a detailed description thereof will be omitted.

When'include','have', and'consist of' mentioned in the present specification are used, other parts may be added unless'only' is used. In the case of expressing the constituent elements in the singular, it includes the case of including the plural unless specifically stated otherwise.

In addition, in the interpretation of the constituent elements, it is interpreted as including an error range even if there is no explicit description.

In "a to b" representing a numerical range in the present specification, "to" is defined as ≥a and ≤b.

According to one aspect, a polyimide film is provided. In the polyimide film derived from the imidation of a polyamic acid formed from the reaction of a dianhydride monomer and a diamine monomer, the inventor of the present invention contains about 10 mol% of biphenyltetracarboxylic acid dianhydride (BPDA) as a dianhydride monomer. To about 90 mol% and satisfying Equation 1 below, it may have a high yield point (eg, a yield point of about 2.2% or more) at a low modulus (eg, a modulus of about 4.5 GPa or less), and As a result, even if the polyimide film was repeatedly deformed, it was found that the degree of damage was small, and the present invention was completed.

The dianhydride monomer is from about 10 mol% to about 90 mol% (e.g., 10 mol%, 15 mol%, 20 mol%, 25 mol%, 30 mol% based on the total molar amount of biphenyltetracarboxylic acid dianhydride). Mol%, 35 mol%, 40 mol%, 45 mol%, 50 mol%, 55 mol%, 60 mol%, 65 mol%, 70 mol%, 75 mol%, 80 mol%, 85 mol% or 90 mol% ) Can be included. In the above range, the elastic section of the polyimide film may be lengthened, and it may be possible to manufacture a polyimide film having a high yield point at a low elastic modulus. For example, the dianhydride monomer is about 15 mol% to about 80 mol%, another example, about 20 mol% to about 70 mol%, based on the total molar amount of the biphenyltetracarboxylic dianhydride dianhydride monomer, another example. For example, it may be included in about 30 mol% to about 50 mol%, but is not limited thereto.

The polyimide film may satisfy Equation 1 below:

Approx. 21 MPa/% ≤ A/B ≤ Approx. 30 MPa/%

In Formula 1, A is the yield strength of the polyimide film, the unit is Mpa, and B is the yield point of the polyimide film, and the unit is %. When A/B is less than about 21 MPa/%, there may be a problem with low tensile strength due to a low yield point, and when A/B exceeds about 30 MPa/%, there is a problem that the low modulus required by the present invention cannot be satisfied. As a result, if the polyimide film is repeatedly deformed, a number of damages may occur. Here, "yield strength" and "yield point" may be measured using a tensile tester based on ASTM D 882 standards, but with a tensile speed of 200 mm/min, but are not limited thereto. According to one embodiment, the A/B value is 21 MPa/%, 22 MPa/%, 23 MPa/%, 24 MPa/%, 25 MPa/%, 26 MPa/%, 27 MPa/%, 28 MPa/% , 29 MPa/% or 30 MPa/%, according to another embodiment, from about 21 MPa/% to about 29 MPa/%, and according to another embodiment, from about 22 MPa/% to about 28 MPa/%, It is not limited.

The polyimide film is about 2 GPa to about 4.5 GPa (e.g., 2 GPa, 2.1 GPa, 2.2 GPa, 2.3 GPa, 2.4 GPa, 2.5 GPa, 2.6 GPa, 2.7 GPa, 2.8 GPa, 2.9 GPa, 3 GPa, 3.1 GPa, 3.2 GPa, 3.3 GPa, 3.4 GPa, 3.5 GPa, 3.6 GPa, 3.7 GPa, 3.8 GPa, 3.9 GPa, 4 GPa, 4.1 GPa, 4.2 GPa, 4.3 GPa, 4.4 GPa or 4.5 GPa) . Here, the "modulus" may be measured using a tensile tester based on the ASTM D 882 standard, but with a tensile speed of 200 mm/min, but is not limited thereto. For example, the modulus of the polyimide film may be about 2 GPa to about 4.2 GPa, for example, about 2.5 GPa to about 4.1 GPa, and for another example, about 2.5 GPa to about 4.0 GPa, but are limited thereto. no.

The polyimide film may further include dianhydride monomers other than biphenyltetracarboxylic dianhydride. As such a dianhydride monomer, various dianhydride monomers may be used without limitation within a range that does not adversely affect the effects of the present invention. Examples of such dianhydride monomers include pyromellitic dianhydride (PMDA). The dianhydride monomers other than biphenyltetracarboxylic dianhydride are based on the total molar amount of the dianhydride monomer, for example, about 10 mol% to about 90 mol% (e.g., 10 mol%, 15 mol%, 20 mol%, 25 Mol%, 30 mol%, 35 mol%, 40 mol%, 45 mol%, 50 mol%, 55 mol%, 60 mol%, 65 mol%, 70 mol%, 75 mol%, 80 mol%, 85 mol% Or 90 mol%), for example from about 20 mol% to about 85 mol%, for another example from about 30 mol% to about 80 mol%, another example from about 50 mol% to about 70 mol% It may be included, but is not limited thereto. For example, pyromellitic dianhydride is based on the total molar amount of dianhydride monomers, for example, about 10 mol% to about 90 mol%, other examples about 20 mol% to about 85 mol%, another example For example, about 30 mol% to about 80 mol%, for another example, may be included in about 50 mol% to about 70 mol%, but is not limited thereto.

As the diamine monomer, various diamine monomers may be used without limitation within a range that does not adversely affect the effects of the present invention. Examples of such diamine monomers include m-tolidine (m-TD), 4,4'-oxydianiline (ODA), 1,3-bis (4-aminophenoxy) benzene (TPE-R), 2,2 -Bis(4-[4-aminophenoxy]-phenyl)propane (PAPP), and the like, and these may be used alone or in combination of two or more, but are not limited thereto.

According to one embodiment, the diamine monomer may include 4,4'-oxydianiline, and in this case, it may be possible to prepare a polyimide film having a high yield point at a low modulus of elasticity. At this time, the content of 4,4'-oxydianiline is, for example, greater than 0 mol% to about 100 mol% (e.g., 1 mol%, 5 mol%, 10 mol%, based on the total number of moles of diamine monomers, 15 mol%, 20 mol%, 25 mol%, 30 mol%, 35 mol%, 40 mol%, 45 mol%, 50 mol%, 55 mol%, 60 mol%, 65 mol%, 70 mol%, 75 mol %, 80 mol%, 85 mol%, 90 mol%, 95 mol% or 100 mol%), for another example from about 50 mol% to about 100 mol%, another example from about 70 mol% to about 100 mol% %, for another example, about 75 mol% to about 100 mol%, another example, about 80 mol% to about 100 mol%, but is not limited thereto.

According to another embodiment, the diamine monomer may include m-tolidine, and in this case, it may be possible to prepare a polyimide film having a high yield point at a low modulus of elasticity. At this time, the content of m-tolidine is, for example, greater than 0 mol% to about 100 mol% (e.g., 1 mol%, 5 mol%, 10 mol%, 15 mol%, based on the total number of moles of the diamine monomer, 20 mol%, 25 mol%, 30 mol%, 35 mol%, 40 mol%, 45 mol%, 50 mol%, 55 mol%, 60 mol%, 65 mol%, 70 mol%, 75 mol%, 80 mol %, 85 mol%, 90 mol%, 95 mol% or 100 mol%), for example greater than 0 mol% to about 50 mol%, another such as greater than 0 mol% to about 30 mol%, another For example, it may be more than 0 mol% to about 25 mol%, for example, more than 0 mol% to about 20 mol%, but is not limited thereto.

According to another embodiment, the diamine monomer may include m-tolidine and 4,4'-oxydianiline, and in this case, the respective effects of m-tolidine and 4,4'-oxydianiline. Is generated synergy, it may be possible to manufacture a polyimide film having a high yield point at a low modulus of elasticity. At this time, the molar ratio of m-tolidine and 4,4'-oxydianiline is about 1:99 to about 99:1 (e.g., 1:99, 5:95, 10:90, 15:85 20:80 , 25:75, 30:70, 35:65, 40:60, 45:55, 50:50, 55:45, 60:40, 65:35, 70:30, 75:25, 80:20, 85 :15, 90:10, 95:5 or 99:1), for example about 1:99 to about 50:50, other for example about 1:99 to about 30:70, for another example about 1 :99 to about 25:75, another example about 1:99 to about 30:70, another example about 1:99 to about 20:80, another example about 5:95 to about 20 It may be: 80, but is not limited thereto. The total amount of m-tolidine and 4,4'-oxydianiline is based on the total number of moles of the diamine monomer, for example, from about 11 mole% to about 100 mole%, other examples from about 50 mole% to about 100 moles. %, for another example, may be about 90 mol% to about 100 mol%, but is not limited thereto.

According to one embodiment, the polyimide film may have a yield strength of about 50 MPa to about 80 MPa (e.g., 50 MPa, 55 MPa, 60 MPa, 65 MPa, 70 MPa, 75 MPa or 80 Mpa). . For example, the yield strength of the polyimide film may be about 50 MPa to about 75 MPa, for example, about 50 MPa to about 70 MPa, and for another example, about 60 MPa to about 70 MPa, but is limited thereto. It is not.

According to one embodiment, the polyimide film is about 2.2% to about 2.9% (e.g., 2.2%, 2.25%, 2.3%, 2.35%, 2.4%, 2.45%, 2.5%, 2.55%, 2.6%, 2.65 %, 2.7%, 2.75%, 2.8%, 2.85% or 2.9%). For example, the polyimide film may have a yield point of about 2.2% to about 2.7%, for example, about 2.2% to about 2.65%, but is not limited thereto.

The thickness of the polyimide film may be appropriately selected in consideration of the use, environment, and physical properties of the polyimide film. For example, the thickness of the polyimide film may be about 10 µm to about 500 µm, for example, about 20 µm to about 50 µm, and another example, about 40 µm to about 50 µm, but is limited thereto. no.

The polyimide film described above may be manufactured by various methods commonly used in the field of manufacturing a polyimide film. For example, the polyimide film is formed by mixing and reacting a dianhydride monomer, a diamine monomer, and an organic solvent to form a polyamic acid solution; Mixing the polyamic acid solution with a dehydrating agent and an imidizing agent to form a polyimide precursor composition; Casting the polyimide precursor composition on a support and drying to prepare a gel film; And, by heat-treating the gel film to form a polyimide film; It can be prepared including steps. Since the description of the dianhydride monomer and the diamine monomer has been described above, a description thereof will be omitted.

First, a polyamic acid may be prepared by reacting a dianhydride monomer and a diamine monomer. More specifically, a polyamic acid solution may be prepared by polymerizing a dianhydride monomer and a diamine monomer in an organic solvent. In this case, all the monomers may be added at once, or each of the monomers may be added sequentially, and in this case, partial polymerization between the monomers may occur.

The organic solvent is not particularly limited as long as it is a solvent in which polyamic acid can be dissolved, and may be, for example, an aprotic polar organic solvent. As non-limiting examples of aprotic polar oil-borne solvents, amide solvents such as N,N'-dimethylformamide (DMF), N,N'-dimethylacetamide (DMAc), p-chlorophenol, o-chloro Phenolic solvents such as phenol, N-methylpyrrolidone (NMP), gamma-butyrolactone (GBL), Diglyme, and the like, and these may be used alone or in combination of two or more. In some cases, an auxiliary solvent such as toluene, tetrahydrofuran, acetone, methyl ethyl ketone, methanol, ethanol, or water may be used to adjust the solubility of the polyamic acid. In one embodiment, the oil cover solvent may be an amide-based solvent, for example, N,N-dimethylformamide or N,N-dimethylacetamide, but is not limited thereto.

Thereafter, a polyimide precursor composition may be formed by mixing a dehydrating agent and an imidizing agent in the polyamic acid solution.

The dehydrating agent is to promote the ring closure reaction through the dehydration action of the polyamic acid, for example, aliphatic acid anhydride, aromatic acid anhydride, N,N'-dialkylcarbodiimide, lower aliphatic halides, halogenated lower fatty acid anhydrides, Arylphosphonic acid dihalide, thionyl halide, and the like, and these may be used alone or in combination of two or more. Among these, aliphatic acid anhydrides such as acetic anhydride, propionic anhydride, and lactic anhydride may be used alone or in combination of two or more from the viewpoints of availability and cost.

The imidizing agent means a component having an effect of accelerating the ring closure reaction with respect to the polyamic acid, and for example, an aliphatic tertiary amine, an aromatic tertiary amine, and a heterocyclic tertiary amine may be used. Among them, a heterocyclic tertiary amine can be used from the viewpoint of reactivity as a catalyst. Examples thereof include quinoline, isoquinoline, β-picoline, pyridine, and the like, and these may be used alone or in combination of two or more.

The amount of the dehydrating agent and the imidizing agent to be added is not particularly limited, but the dehydrating agent is from about 0.5 mol to about 5 mol (e.g., 0.5 mol, 1 mol, 1.5 mol, 2 mol, 2.5 mol, based on 1 mol of the amic acid group in the polyamic acid). Mol, 3 mol, 3.5 mol, 4 mol, 4.5 mol or 5 mol), for example, can be added in a ratio of about 1.0 mol to about 4 mol, and the imidizing agent is about 1 mol of the amic acid group in the polyamic acid. 0.05 moles to about 3 moles (e.g., 0.05 moles, 0.1 moles, 0.5 moles, 1 moles, 1.5 moles, 2 moles, 2.5 moles or 3 moles), such as about 0.2 moles to about 2 moles It may be, and the imidization within the above range may be sufficient, and it may be easy to cast in a film form.

According to one embodiment, the polyamic acid is about 5% by weight to about 35% by weight (e.g., 5% by weight, 10% by weight, 15% by weight, 20% by weight, 25% by weight) based on the total weight of the polyimide precursor composition. % By weight, 30% by weight or 35% by weight). In this range, the precursor composition may have a molecular weight and a solution viscosity suitable for forming a film. Based on the total weight of the precursor composition, the polyamic acid may be included in, for example, about 10% by weight to about 30% by weight, for example, about 15% by weight to about 20% by weight, but is not limited thereto.

According to one embodiment, the polyimide precursor composition is from about 100,000 cP to about 500,000 cP (e.g., 100,000 cP, 150,000 cP, 200,000 cP, 250,000 cP, 300,000 cP, 350,000 cP, 400,000 cP, 450,000 cP or 500,000 cP). In the above range, while the polyamic acid has a predetermined weight average molecular weight, processability may be excellent when forming a polyimide film. Here,'viscosity' may be measured using a Brookfield viscometer. The precursor composition may have a viscosity of about 150,000 cP to about 450,000 cP, for example about 200,000 cP to about 400,000 cP, another example about 250,000 cP to about 350,000 cP, at 25° C. It is not limited.

Thereafter, the polyimide precursor composition may be cast on a support and dried to prepare a gel film.

As the support, a support commonly used in the art may be used without limitation, and examples of such a support include a glass plate, an aluminum foil, an endless stainless belt, and a stainless drum.

Drying is, for example, about 40° C. to about 300° C., for example about 80° C. to about 200° C., another example, about 100° C. to about 180° C., another example about 100° C. to about 130° C. It can be carried out at a temperature of °C, whereby the dehydrating agent and the imidizing agent are activated, and a gel film can be formed by partially curing and/or drying. The gel film is in an intermediate stage of curing from polyamic acid to polyimide, and may have self-supporting properties.

In some cases, it may include the step of stretching the gel film to adjust the thickness and size of the finally obtained polyimide film and improve orientation, and the stretching may be performed in a machine transport direction (MD) and a transverse direction to the machine transport direction. It may be performed in at least one direction of (TD).

The volatile content of the gel film is, but is not limited to, about 5% to about 500% by weight, for example, about 5% to about 200% by weight, and other examples about 5% to about 150% by weight. In the above range, there may be an effect of avoiding occurrence of defects such as film breakage, uneven color tone, and characteristic fluctuation during the process of heat treatment to obtain a polyimide film afterwards. Here, the volatile content of the gel film can be calculated using Equation 2 below. In Equation 2, C denotes the weight of the gel film, and D denotes the weight after heating the gel film at 450° C. for 20 minutes.

(C-D)*100/D

According to one embodiment, in the step of heat-treating the gel film, the gel film is varied in the range of about 50° C. to about 700° C., for example, about 150° C. to about 600° C., and other examples, about 200° C. A polyimide film can be obtained by heat treatment at a phosphorus temperature to remove a solvent, etc. remaining in the gel film, and imidizing most of the remaining amic acid groups.

In some cases, the polyimide film obtained as described above may be further cured by heating and finishing at a temperature of about 400° C. to about 650° C. for about 5 seconds to about 400 seconds to further cure the polyimide film. You may do this under a certain tension in order to alleviate the internal stress that may be.

Hereinafter, the configuration and operation of the present invention will be described in more detail through preferred embodiments of the present invention. However, this has been presented as a preferred example of the present invention and cannot be construed as limiting the present invention in any sense.

실시예Example

실시예 1 내지 13 및 비교예 1 내지 3Examples 1 to 13 and Comparative Examples 1 to 3

In dimethylformamide (DMF), 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride as a dianhydride monomer, m-tolidine (m-TD) as a diamine monomer, and 4,4'-oxydianiline (ODA) was mixed at the molar ratio shown in Table 1 below and then polymerized to prepare a polyamic acid solution having a solid content of 18.5% by weight. At this time, the number of moles of the dianhydride monomer and the diamine monomer were substantially equimolar.

A composition for preparing a polyimide film was obtained by adding 3.5 molar ratio of acetic anhydride and 1.1 molar ratio of isoquinoline per 1 mol of amic acid group to the thus prepared polyamic acid solution, and the composition was placed on a SUS plate (100SA, Sandvik Co., Ltd.) using a doctor blade. Cast and dried at 90° C. for 4 minutes to prepare a gel film. After separating the gel film from the SUS plate, heat treatment was performed at 250 to 380° C. for 14 minutes to prepare a polyimide film having an average thickness of 50 μm.

However, in the case of Comparative Example 3, a polyimide film was not prepared.

평가예: 모듈러스(단위: GPa), 항복점(단위: %), 항복강도(단위: Mpa)의 측정Evaluation example: Measurement of modulus (unit: GPa), yield point (unit: %), and yield strength (unit: Mpa)

The prepared polyimide film was cut into 15 mm × 50 mm to prepare a specimen, and according to ASTM D 882 standard, but with a tensile speed of 200 mm/min, a tensile tester (Instron 5564, Instron) was used to obtain a room temperature. .), the modulus, yield point, and yield strength were measured, and the results are shown in Table 1 below.

		이무수물 단량체(몰%)Dianhydride monomer (mol%)		디아민 단량체(몰%)Diamine monomer (mol%)		폴리이미드 필름 특성Polyimide film properties
		BPDABPDA	PMDAPMDA	m-TDm-TD	ODAODA	모듈러스(GPa)Modulus (GPa)	항복점(%)yield point(%)	항복강도(MPa)Yield strength (MPa)	항복강도/항복점(MPa/%)Yield strength/Yield point (MPa/%)
실시예Example	1One	1010	9090	--	100100	2.52.5	2.42.4	55.0555.05	22.922.9
	22	2525	7575	2020	8080	4.084.08	2.462.46	68.0968.09	27.6827.68
	33	2525	7575	1515	8585	3.963.96	2.262.26	61.2361.23	27.0927.09
	44	2525	7575	--	100100	2.702.70	2.452.45	60.060.0	24.4924.49
	55	3030	7070	1515	8585	3.873.87	2.322.32	61.6561.65	26.5726.57
	66	3535	6565	1515	8585	3.943.94	2.292.29	61.3561.35	26.7926.79
	77	3535	6565	1010	9090	3.663.66	2.292.29	59.359.3	25.9025.90
	88	3535	6565	55	9595	3.583.58	2.242.24	55.4155.41	24.7424.74
	99	3535	6565	--	100100	3.263.26	2.362.36	55.1655.16	23.3723.37
	1010	5050	5050	1010	9090	3.73.7	2.32.3	59.359.3	25.7825.78
	1111	5050	5050	--	100100	3.303.30	2.502.50	63.063.0	25.2025.20
	1212	7070	3030	--	100100	3.453.45	2.602.60	65.065.0	25.0025.00
	1313	9090	1010		100100	3.603.60	2.622.62	65.165.1	24.8424.84
비교예Comparative example	1One	--	100100	--	100100	2.42.4	2.162.16	49.2249.22	20.0120.01
	22	5050	5050	3030	7070	4.64.6	2.492.49	77.0077.00	30.9230.92
	33	100100	--	--	100100	--

As can be seen from Table 1, Examples 1 to 13 in which the content of BPDA and the value according to Equation 1 satisfy the scope of the present invention have a high yield point while having a low modulus falling within the scope of the present invention, As a result, it is easily predicted that the degree of damage to the repetitive deformation applied to the polyimide film will be small.

On the other hand, the polyimide film of Comparative Example 1 in which the BPDA content did not reach the scope of the present invention and the value according to Equation 1 did not reach the scope of the present invention had a yield point as low as 2.16%. Although the content of BPDA falls within the scope of the present invention, the polyimide film of Comparative Example 2 in which the value according to Equation 1 is out of the scope of the present invention has a high modulus of 4.6 GPa. Accordingly, it is predicted that the polyimide films of Comparative Examples 1 and 2 will have a large degree of damage when repeatedly deformed.

On the other hand, in the case of Comparative Example 3 in which the content of BPDA exceeds the scope of the present invention, it was impossible to manufacture a polyimide film when the above-described manufacturing method was applied.

Simple modifications or changes of the present invention can be easily implemented by those of ordinary skill in the art, and all such modifications or changes can be considered to be included in the scope of the present invention.

Claims

It is a polyimide film derived from imidization of a polyamic acid formed from the reaction of a dianhydride monomer and a diamine monomer,

The dianhydride monomer includes biphenyltetracarboxylic dianhydride (BPDA) in an amount of about 10 mol% to about 90 mol% based on the total molar amount of the dianhydride monomer,

The polyimide film satisfies the following formula 1, and has a modulus of about 2 GPa to about 4.5 GPa:

<Equation 1>

Approx. 21 MPa/% ≤ A/B ≤ Approx. 30 MPa/%

In Formula 1, A is the yield strength of the polyimide film, the unit is Mpa, and B is the yield point of the polyimide film, and the unit is %.
The method of claim 1,

The dianhydride monomer is a polyimide film further comprising pyromellitic dianhydride (PMDA).
The method of claim 2,

The pyromellitic dianhydride is a polyimide film containing about 10 mol% to about 90 mol% based on the total molar amount of dianhydride monomers.
The method according to any one of claims 1 to 3,

The diamine monomer is m-tolidine (m-TD), 4,4'-oxydianiline (ODA), 1,3-bis (4-aminophenoxy) benzene (TPE-R), 2,2-bis A polyimide film comprising (4-[4-aminophenoxy]-phenyl)propane (PAPP) or a combination thereof.
The method of claim 4,

The diamine monomer is a polyimide film comprising m-tolidine (m-TD) and 4,4'-oxydianiline (ODA) in a molar ratio of about 1:99 to about 20:80.
The method according to any one of claims 1 to 5,

The polyimide film has a yield strength of about 50 MPa to about 80 MPa.
The method according to any one of claims 1 to 6,

The polyimide film has a yield point of about 2.2% to about 2.9%.
It is a manufacturing method of the polyimide film of any one of claims 1 to 7, wherein the method,

Mixing and reacting a dianhydride monomer, a diamine monomer, and an organic solvent to form a polyamic acid solution;

Mixing the polyamic acid solution with a dehydrating agent and an imidizing agent to form a polyimide precursor composition;

Casting the polyimide precursor composition on a support and drying to prepare a gel film; And,

Heat-treating the gel film to form a polyimide film;

Polyimide film manufacturing method comprising the step.
The method of claim 8,

The heat treatment is performed at about 100° C. to about 700° C., a method for producing a polyimide film.