WO2020138645A1 - Polyamic acid composition and transparent polyimide film using same - Google Patents

Abstract

The present invention provides a polyamic acid composition comprising triamine having a specific structure capable of forming cross-linking bonds, a polyamic acid formed from the polyamic acid composition, and a transparent polyimide film having improved optical characteristics and mechanical characteristics at the same time through imidization of the polyamic acid.

Description

Polyamic acid composition, and transparent polyimide film using same

The present invention is a polyamic acid composition comprising a triamine having a specific structure capable of forming a crosslink, a polyamic acid formed from the composition, and imidizing the polyamic acid to a transparent polyimide film having improved optical and mechanical properties simultaneously It is about.

A polyimide (PI) resin generally refers to a high heat-resistant resin produced by solution polymerization of an aromatic dianhydride and an aromatic diamine or an aromatic diisocyanate to produce a polyamic acid derivative, followed by dehydration at a high temperature by dehydration. Since these polyimide resins are insoluble and non-melting ultra-high heat-resistant resins, they have excellent properties such as heat oxidation resistance, heat resistance, radiation resistance, low temperature properties, and chemical resistance, and heat-resistant high-tech materials such as automotive materials, aviation and spacecraft materials, and insulation It is used in a wide range of fields for electronic materials such as coatings, insulating films, semiconductors, and electrode protective films for LCDs.

However, the polyimide (PI) resin is colored brown or yellow due to the high aromatic ring density, and thus has low transmittance in the visible region, so it is difficult to use in a field requiring transparency. Recently, a colorless and transparent polyimide film has been developed. In this case, the coefficient of thermal expansion (CTE) is higher than that of the existing polyimide resin, and the solvent resistance is deteriorated. Accordingly, when a colorless and transparent polyimide is used for a substrate, an optical coating, and a film, there is a problem in that bending or twisting is likely to occur due to a high coefficient of thermal expansion. Accordingly, in order to be applied as a display material, excellent optical and mechanical properties of the polyimide film must be supported.

As a result, there is a need to develop a composition for forming a polyamic acid having excellent mechanical properties while exhibiting high transparency and low yellowness.

The present invention has been made to solve the above-mentioned problems, and has an object to provide a polyamic acid composition comprising a triamine monomer having a specific chemical structure capable of forming a crosslink as a component of a composition for forming a polyamic acid. .

In addition, the present invention provides a transparent polyimide film formed from the above-described polyamic acid composition and comprising polyamic acid in the molecule, and imidized using the polyamic acid to simultaneously realize excellent optical and mechanical properties. It aims to do.

In order to achieve the above object, the present invention is at least one diamine; At least one dianhydride; And it provides a polyamic acid composition comprising a triamine represented by the formula (1).

In Chemical Formula 1,

A ₁ is a C ₆ ~ C ₃₀ aromatic or C ₅ ~ C ₃₀ alicyclic organic group, the aromatic and alicyclic organic groups are each independently a monocyclic ring, or at least two rings are directly or through a bridge structure ,

Y ₁ to Y ₃ are the same as or different from each other, each independently a single bond or -O-, -S-, -SO ₂ -, -COO-, -OCO-, C ₂ ~ C ₃₀ alkenyl group, C ₄ ~ C _{30 It} is selected from the group consisting of a cycloalkylene group and C ₆ ~ C ₃₀ arylene group,

B ₁ to B ₃ are the same as or different from each other, and each independently a C ₆ to C ₃₀ aromatic or C ₅ to C ₃₀ alicyclic organic group, and the aromatic and alicyclic organic groups are each independently a monocyclic ring, or At least two rings are connected directly or through a crosslinked structure,

R _a , R _b and R _c are the same as or different from each other, and each independently selected from the group consisting of hydrogen, halogen, cyano group, nitro group, C ₁ to C ₄₀ alkyl group, and -CF ₃ ,

o, p and q are each independently an integer from 0 to 4,

R ₁₁ , R ₁₂ , R ₂₁ , R ₂₂ , R ₃₁ and R ₃₂ are the same as or different from each other, and each independently hydrogen, halogen, cyano group, nitro group, C ₁ to C ₄₀ alkyl group, and -CF ₃ Is selected from the group consisting of,

In the A ₁ , Y ₁ ~ Y ₃ , B ₁ ~ B ₃ , R _a ~ R _c , R ₁₁ , R ₁₂ , R ₂₁ , R ₂₂ , R ₃₁ and R ₃₂ , each hydrogen is independently halogen and -CF ₃ It may be substituted with one or more substituents selected from the group consisting of.

In addition, the present invention provides a polyamic acid formed using the above-described polyamic acid composition.

In addition, the present invention provides a transparent polyimide film formed by imidizing the aforementioned polyamic acid composition.

In the present invention, by using a triamine monomer having a specific structure as a reactant and a crosslinker forming a polyamic acid, a three-dimensional network structure is formed through a crosslinking reaction to simultaneously exhibit high light transmittance, low yellowness and excellent mechanical properties. Can.

In addition, in the present invention, by applying the above-described polyamic acid composition to impart high light transmittance and excellent mechanical properties as a substrate, it is possible to provide a flexible display substrate exhibiting excellent physical properties and product reliability.

The effects according to the present invention are not limited by the contents exemplified above, and more various effects are included in the present specification.

Hereinafter, the present invention will be described in detail. However, this is presented as an example, and the present invention is not limited thereby, and the present invention is only defined by the scope of the claims described in the specification.

<Polyamic acid composition>

The polyamic acid composition of the present invention is a precursor composition for forming a polyamic acid for preparing a transparent polyimide film, and is characterized by comprising triamine represented by the formula (1).

Specifically, the polyamic acid composition may include at least one diamine monomer, at least one dianhydride monomer; And at least one triamine monomer having a specific structure capable of acting as a reactant and a crosslinking agent.

The compound represented by Formula 1 is a triamine-based compound containing three amine groups in the molecule. When such a triamine is used as a component of a polyamic acid composition, three amine groups react with a crosslinking functional group to form a crosslink of a three-dimensional network structure in the molecule, making it more rigid and rigid than a polyamic acid having a conventional linear structure. ) And a high molecular weight polyamic acid is produced. Since the polyamic acid is not decomposed by heat or light and is more stable against external impact, the optical properties, thermal properties, and mechanical properties (Modulus, Strength), etc. of the transparent polyimide resin manufactured using the polyamic acid are significantly improved. Can.

Particularly, a crosslinking agent was added to improve the physical properties of the conventional polyamic acid, but since the crosslinking agent is simply used as an additive, the amount of reactants (e.g., diamine and dianhydride) is reduced by the amount added, resulting in the final polyamic acid. Deterioration in physical properties may result. In addition, since a crosslinking agent must be separately added after forming the solution-polymerized polyamic acid, the number of manufacturing processes may be added, and mass productivity may be deteriorated. In contrast, in the present invention, by using a triamine monomer having a specific structure as a reactant (eg, amine monomer) forming a polyamic acid and a crosslinker capable of forming a crosslink, the above-mentioned problems are not caused fundamentally. .

In addition, since the triamine contains at least one electron withdrawing group (EWG) such as fluorine (F) or -CF ₃ in the molecular skeleton, the aforementioned optical properties, mechanical properties, and thermal properties can be further increased. More specifically, the polyimide film has a dark brown color, not colorless, because of the charge transfer complex (CTC) of π electrons present in the imide chain. Since -F, -CF ₃ and the like introduced in Chemical Formula 1 are strong electron-withdrawing groups, the CT-Complex does not occur through movement between π electrons, thereby exhibiting high transparency of polyimide.

The triamine contained in the polyamic acid composition according to the present invention includes at least one compound represented by the formula (1).

For example, in Formula 1, A ₁ may be a hydrocarbon-based cyclic group containing at least one hydrocarbon-based or heteroatom known in the art. In addition, they may be condensed, fused, bridged with other adjacent rings or spirocyclic. As an example, A ₁ may be selected from the group consisting of monocyclic or polycyclic alicyclic ring, monocyclic or polycyclic heteroalicyclic ring, monocyclic or polycyclic aromatic ring, or monocyclic or polycyclic heteroaromatic ring. . Specifically, A ₁ is a C ₆ ~ C ₃₀ aromatic or C ₅ ~ C ₃₀ alicyclic organic group, the aromatic and alicyclic organic groups are each independently a monocyclic ring, or at least two polycyclic rings are directly or crosslinked structure It may be connected through. For a more specific example, A ₁ may be a monocyclic or polycyclic C ₆ to C ₂₀ aromatic or C ₅ to C ₂₀ alicyclic organic group, and preferably a phenyl group.

In addition, Y ₁ to Y ₃ are the same as or different from each other, each independently a single bond or -O-, -S-, -SO ₂ -, -COO-, -OCO-, C ₂ ~ C ₃₀ alkenyl group , C ₄ ~ C ₃₀ It may be selected from the group consisting of a cycloalkylene group and C ₆ ~ C ₃₀ arylene group. Specifically, Y ₁ to Y ₃ are the same as or different from each other, and may each independently be -O-.

B ₁ to B ₃ are the same as or different from each other, and each independently may be a hydrocarbon-based ring group containing at least one hydrocarbon-based or heteroatom known in the art. Specifically, B ₁ to B ₃ may each independently be the same as A ₁ described above, and each independently C ₆ to C ₃₀ aromatic or C ₅ to C ₃₀ alicyclic organic group, the aromatic and alicyclic organic The groups may be each independently a monocyclic ring, or at least two polycyclic rings may be directly or linked through a crosslinked structure. For a more specific example, B ₁ to B ₃ are the same as or different from each other, and each independently may be a monocyclic or polycyclic C ₆ to C ₂₀ aromatic or C ₅ to C ₂₀ alicyclic organic group, preferably All of B ₁ to B ₃ may be a phenyl group.

If A ₁ , Y ₁ to Y ₃ , and B ₁ to B ₃ of Formula 1 according to an embodiment of the present invention are more concretely expressed, they may be represented by the following Formula 2.

[Formula 2]

In the above formula,

R _a , R _b , R _c , R ₁₁ , R ₁₂ , R ₂₁ , R ₂₂ , R ₃₁ , R ₃₂ , o, p, and q are each as defined in Formula 1.

In the aforementioned B ₁ to B ₃ , R _a to R _c may be substituted as various substituents, respectively. These R _a , R _b and R _c are the same as or different from each other, and each independently can be selected from the group consisting of hydrogen, halogen, cyano group, nitro group, C ₁ to C ₄₀ alkyl group, and -CF ₃ . . Specifically, R _a to R _c may each be a conventional electron withdrawing group (EWG) known in the art, and each independently halogen (X = F, Cl, Br, such as fluorine (F)), I) or CF ₃ is preferred.

In this case, the number of R _a to R _c substitutions (eg, o, p and q) is not particularly limited, and for example, o, p and q may each independently be an integer from 0 to 4, but o+p It can be +q >1. Specifically, 1 <o+p+q ≤ 6, and preferably, o, p, and q may each be 1. Here, when o is 0, R _a is hydrogen, and when o is 1 to 4, R _a has the aforementioned substituents except hydrogen. In addition, when p is 0, R _b is hydrogen, and when p is 1 to 4, R _b has the aforementioned substituents except hydrogen. And, when q is 0, R _c is hydrogen, and when q is 1 to 4, R _c has the aforementioned substituents excluding hydrogen.

According to an embodiment of the present invention, each R _a , R _b , and R _c introduced into B ₁ to B ₃ of Formula 1 may be more specifically represented by Formula 3 below. However, it is not limited thereto.

[Formula 3]

In the above formula,

R ₁₁ , R ₁₂ , R ₂₁ , R ₂₂ , R ₃₁ , R ₃₂ , o, p, and q are each as defined in Formula 1.

In addition, R ₁₁ , R ₁₂ , R ₂₁ , R ₂₂ , R introduced into three amine groups of the triamine represented by Formula 1 (eg, -NR ₁₁ R ₁₂ , -NR ₂₁ R ₂₂ , -NR ₃₁ R ₃₂ ) ₃₁ and R ₃₂ are the same as or different from each other, and each independently may be selected from the group consisting of hydrogen, halogen, cyano group, nitro group, C ₁ to C ₄₀ alkyl group, and -CF ₃ . Specifically, R ₁₁ , R ₁₂ , R ₂₁ , R ₂₂ , R ₃₁ and R ₃₂ may each independently be hydrogen or an alkyl group of C ₁ to C ₄₀ , and more specifically, all hydrogen.

In A ₁ , Y ₁ to Y ₃ , B ₁ to B ₃ , R _a to R _c , R ₁₁ , R ₁₂ , R ₂₁ , R ₂₂ , R ₃₁ and R ₃₂ of Formula 1 described above, any hydrogen is Each may be independently substituted with one or more substituents selected from the group consisting of halogen (X = F, Cl, Br, I) and -CF ₃ .

The amount of the triamine monomer represented by Formula 1 according to the present invention is not particularly limited, and for example, it may be 1 to 20 mol% based on 100 mol% of the total amine combined with the diamine and triamine, preferably 5 to 20 mol%. When the content of triamine is added in the above-described content range, a polyamic acid having a more robust chemical structure and high molecular weight may be formed.

Meanwhile, in the present invention, the use of the above-described triamine as one of the reactants (for example, amine monomer) forming the polyamic acid is specifically illustrated. However, the present invention is not limited thereto, and it is also within the scope of the present invention to add as a crosslinking agent to the polyamic acid that is the result of solution polymerization of diamine and dianhydride. As such, when used as a crosslinking agent added to a solution-polymerized polyamic acid, the content of the triamine may be appropriately adjusted within the content range of additives known in the art. In one example, the content of the triamine may be 0.1 to 20 parts by weight based on the total weight of the polyamic acid composition, preferably 0.5 to 15 parts by weight. At this time, the total weight of the polyamic acid composition may mean the total amount of monomers excluding the solvent.

The polyamic acid composition of the present invention contains at least one diamine compound known in the art.

The diamine compound may be used without particular limitation as long as it is a compound having a diamine structure in the molecule, and for example, an aromatic, alicyclic, or aliphatic compound having a diamine structure. Specifically, the diamine compound is a non-fluorine aromatic diamine known in the art, a fluorinated aromatic diamine having a fluorine substituent introduced, a sulfone-based diamine, a hydroxy-based diamine, an ether-based diamine, an alicyclic diamine, respectively, or two or more kinds. Can be used interchangeably.

Non-limiting examples of diamines that can be used include oxydianiline (ODA), 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (2,2'-TFDB), 2 ,2'-bis(trifluoromethyl)-4,3'-diaminobiphenyl (2,2'-Bis(trifluoromethyl) -4,3'-Diaminobiphenyl), 2,2'-bis (trifluoro Methyl)-5,5'-diaminobiphenyl (2,2'-Bis(trifluoromethyl) -5,5'-Diaminobiphenyl), 2,2'-bis(trifluoromethyl)-4,4'-di Aminophenyl ether (2,2'-Bis (trifluoromethyl)-4,4'-diaminodiphenyl ether, 6-FODA), bis aminohydroxy phenyl hexafluoropropane (DBOH), bis amino phenoxy phenyl hexafluoropropane ( 4BDAF), bis amino phenoxy phenylpropane (6HMDA), bis aminophenoxy diphenylsulfone (DBSDA), bis (4-aminophenyl) sulfone (4,4'-DDS), bis (3-aminophenyl) sulfone ( 1, selected from the group consisting of 3,3'-DDS), sulfonyldiphthalanhydride (SO2DPA), 4,4'-oxydianiline (4,4'-ODA), bis(carboxyphenyl) dimethylsilane It may be abnormal. The above-described diamines may be used alone or in a mixture of two or more of them.

Considering high transparency, high glass transition temperature, and low yellowness, the fluorinated diamine is a 2,2'-bis(trifluoro methyl)-4,4'-diamino ratio capable of inducing linear polymerization. Phenyl (2,2'-TFDB) can be used. In addition, bis(4-aminophenyl)sulfone (4,4'-DDS) can be used as the sulfone-based diamine, and the hydroxy diamine is 2,2-bis (3-amino-4-methylphenyl)-hexafluoro. Propane (2,2-Bis (3-amino-4-methylphenyl)-hexafluoropropane, BIS-AT-AF) can be used. In addition, as the ether-based diamine, 2,2'-bis(trifluoromethyl)-4,4'-diaminophenyl ether (6-FODA) or oxidianiline (ODA) may be used.

According to a preferred example of the present invention, the use ratio of the diamine and triamine may be 80 to 99: 1 to 20 mol% ratio, specifically 90 to 95: 5 to 10 mol% ratio.

In addition, the dianhydride (b) monomer used in the polyamic acid production of the present invention can be used without limitation a compound known in the art having an intramolecular dianhydride structure. Specifically, conventional fluorinated, non-fluorinated, cycloaliphatic dianhydrides and the like known in the art may be used alone or in combination of two or more.

The fluorinated dianhydride monomer is not particularly limited as long as it is an aromatic dianhydride in which a fluorine substituent is introduced. One example of a fluorinated dianhardide that can be used is 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydrid, 6- FDA), 4-(trifluoromethyl)pyromellitic dianhydride (4-TFPMDA), and the like. These may be used alone or in combination of two or more. Among the fluorinated dianhydrides, 6-FDA is a compound suitable for clarification due to its very large property that limits the formation of a charge transfer complex (CTC) between molecular chains and in molecular chains.

In addition, the alicyclic (alicyclic) dianhydride is not particularly limited as long as it is a compound having an dianhydride structure while having an alicyclic ring rather than an aromatic ring in the compound. Examples of usable alicyclic dianhydrides include cyclobutane tetracarboxylic dianhydride (CBDA), 1,2,3,4-cyclopentane tetracarboxylic dianhydride (CPDA) and bicyclo[2 ,2,2]-7-octene-2,3,5,6-tetracarboxylic dianhydride (BCDA), and the like, but are not particularly limited thereto. Each of the aforementioned dianhydrides may be used alone, or two or more of them may be used in a mixed form.

The non-fluorinated dianhydride monomer is not particularly limited as long as it is a non-fluorinated aromatic dianhydride to which a fluorine substituent is not introduced. Non-limiting examples of non-fluorinated dianhydride monomers that can be used include pyromellitic dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (3,3 ′,4,4′-Biphenyl tetracarboxylic acid dianhydride (BPDA), benzophenone tetracarboxylic dianhydride (BTDA), oxydiphthalic dianhydride (ODPA), and the like. These may be used alone, or two or more of them may be used in combination.

Specific examples of dianhydrides that can be used include pyromellitic dianhydride (PMDA), biphenyltetracarboxylic dianhydride (BPDA), and 2,2-bis(3,4-dicarboxyphenyl)hexafluoro. Lopropane dianhydride (2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydrid, 6-FDA), 4,4'-bisphenol A dianhydride (BPADA), 4 -(Trifluoromethyl)pyromellitic dianhydride (4-TFPMDA), cyclobutane tetracarboxylic dianhydride (CBDA), 1,2,3,4-cyclopentane 1 selected from the group consisting of tetracarboxylic dianhydride (CPDA), and bicyclo[2,2,2]-7-octene-2,3,5,6-tetracarboxylic dianhydride (BCDA) It may be more than a species.

In the polyamic acid composition of the present invention, the ratio (a/b) of the number of moles of the total amine component (a) combined with the diamine and triamine and the number of moles of the dianhydride component (b) may be 0.7 to 1.3, It is preferably from 0.8 to 1.2, and more preferably from 0.9 to 1.1.

The polyamic acid composition of the present invention, as a solvent (c) for solution polymerization of the above-mentioned monomers, can be used without limitation an organic solvent known in the art.

Examples of usable solvents are m-cresol, N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAc), dimethylsulfoxide (DMSO), acetone, diethyl Acetate, and one or more polar solvents selected from dimethyl phthalate (DMP) may be used. In addition, a low boiling point solution such as tetrahydrofuran (THF) or chloroform or a solvent such as γ-butyrolactone can be used. In addition, the content of the solvent is not particularly limited, in order to obtain a molecular weight and viscosity of a suitable polyamic acid solution, the content of the polymerization solvent is preferably 50 to 95% by weight based on the total weight of the polyamic acid composition, more preferably It may be 70 to 90% by weight.

In the present invention, the above-described dianhydride, diamine and triamine are added to a solvent and reacted to prepare a transparent polyamic acid composition. As an example, a triamine of Formula 1, at least one or more diamine components, and at least one dianhydride, but include an amine (a) and a dianhydride (b) approximately to improve the glass transition temperature and yellowness. A transparent polyamic acid composition can be formed at an equivalent ratio of 1:1.

The composition of the polyamic acid composition is not particularly limited, and for example, based on 100% by weight of the total weight of the polyamic acid composition, satisfies 2.5 to 25.0% by weight of dianhydride, 2.5 to 25.0% by weight of diamine, and 100% by weight of composition It can be configured to include the remaining amount of the organic solvent. In one example, the content of the organic solvent may be 70 to 90% by weight. In addition, in the present invention, when it is based on 100% by weight of solid content, it may be in the range of 30 to 70% by weight of dianhydride and 30 to 70% by weight of diamine, but is not particularly limited thereto.

The transparent polyamic acid composition of the present invention configured as described above may have a viscosity in the range of about 1,000 to 400,000 cps, preferably about 5,000 to 100,000 cps. When the viscosity of the polyamic acid solution falls within the above-described range, the thickness can be easily adjusted when the polyamic acid solution is coated, and the coating surface can be uniformly exhibited.

In addition, the polyamic acid composition described above may further include at least one additive known in the art within a range not significantly impairing the object and effect of the present invention, if necessary. Examples of such additives include plasticizers, antioxidants, flame retardants, dispersants, viscosity modifiers, leveling agents, and the like. In addition, the additive may be added by appropriately adjusting within the range of the amount used in the art.

<polyamic acid>

The present invention provides a polyamic acid formed using the polyamic acid composition described above. Specifically, the polyamic acid includes a repeating unit represented by Formula 4 below.

[Formula 4]

In the above formula,

PAA is a polyamic acid derived from the polymerization of diamine and dianhydride or a derivative thereof,

A ₁ , Y ₁ to Y ₃ , B ₁ to B ₃ , R _a , R _b , R _c , R ₁₁ , R ₁₂ , R ₂₁ , R ₂₂ , R ₃₁ , R ₃₂ , o, p, and q are respectively As defined in Formula 1.

For example of the present invention, the PAA may be more specifically expressed as a repeating unit represented by any one of the following Chemical Formulas 5 to 7.

[Formula 5]

[Formula 6]

[Formula 7]

In the above formula 5 to 7,

Ar ₁ is a divalent organic group derived from an alicyclic diamine or aromatic diamine, and a plurality of Ar ₁ are the same or different from each other,

Ar ₂ is a tetravalent organic group derived from an alicyclic dianhydride or aromatic dianhydride, wherein a plurality of Ar ₂ are the same or different from each other,

n is an integer of 1 or more, specifically, an integer between 1 and 10,000.

For a specific example of the present invention, the PAA may include repeating units represented by the following Chemical Formulas 8 or 9.

[Formula 8]

[Formula 9]

In Chemical Formulas 8 and 9,

Ar ₁₁ to Ar ₁₅ are the same or different from each other, and each independently a divalent organic group derived from an alicyclic diamine or an aromatic diamine,

Ar ₂₁ to Ar ₂₅ are the same or different from each other, and each independently a tetravalent organic group derived from an alicyclic dianhydride or aromatic dianhydride,

n1 and n2 are each an integer between 1 and 10000, provided that n1+n2≥1,

m1 and m2 are each an integer between 1 and 10000, provided that m1+m2≥1.

In the above-described formulas 5 to 9, Ar ₁ derived from an alicyclic or aromatic diamine, specifically Ar ₁₁ to Ar ₁₅ may be more specifically represented by the following formula (10).

[Formula 10]

In Chemical Formula 10,

Ring Cy ₁ and ring Cy ₂ are the same or different from each other, and each independently a C ₄ ~ C ₂₀ monocyclic aliphatic ring, C ₄ ~ C ₂₀ polycyclic aliphatic ring, C ₆ ~ C ₂₀ monocyclic aromatic ring and C ₆ ~ C _{20 It} is selected from the group consisting of a polycyclic aromatic ring,

Aliphatic ring, an aromatic ring of the ring ₁ and ring Cy Cy ₂ are each independently a C ₁ ~ C ₂₀ alkyl group and a C ₁ ~ _C20 of halo-substituted or unsubstituted by one or more substituent species selected from the group consisting of alkyl ring,

x is 0 or 1,

Ar ₃ is a single bond, -O-, -S-, -S(=O) ₂ -, -C(=O)-, -C(=O)NH-, C ₁ ~ C ₆ alkylene group, C An arylene group of ₆ to C ₂₀ ,

And

Is selected from the group consisting of,

W is selected from the group consisting of C ₁ ~ C ₂₀ alkylene group, C ₁ ~ C ₂₀ haloalkylene group and -SO _2- (preferably -(CH ₂ )-, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -and -SO ₂ -.

For one embodiment of the present invention, Ar ₃ may be selected from the group of substituents represented by the following structural formula.

Also, for example of Ar ₂ derived from an alicyclic or aromatic dianhydride, specifically Ar ₂₁ to Ar ₂₅ , these are C ₄ to C ₂₀ tetravalent monocyclic aliphatic ring groups, C ₄ to C ₂₀ tetravalent, respectively. polycyclic aliphatic cyclic group, C ₆ ~ ₄₀ 4 is a monocyclic aromatic group, and the monocyclic 4, C ₆ ~ ₄₀ are selected from the group consisting of an aromatic ring,

At this time, when Ar ₂ is a plurality of ring groups, the plurality of ring groups are the same or different from each other, and each ring group is -C(=O)-, -C(=O)NH-, -C(=O)-O- , -S(=O) ₂ -, -S-, -O-, C ₁ ~ C ₆ alkylene group, and one or more linkers selected from the group consisting of C ₁ ~ C ₆ haloalkylene group, or Or it can be non-connected.

For one embodiment of the present invention, Ar ₂ and Ar ₂₁ to Ar ₂₅ may be each independently selected from the group of substituents represented by the following structural formula.

For a preferred example of the present invention, the polyamic acid may be more specifically represented by a compound represented by the following Chemical Formula 4a.

[Formula 4a]

In the above formula,

PAA is the same as defined in the above formula (4), preferably may be any one selected from the group represented by the formula 5 to formula 9.

R ₁₁ , R ₂₁ , R ₃₁ , R ₃₂ , o, p, and q are each as defined in Formula 1.

<Transparent polyimide film>

In addition, the present invention provides a transparent polyimide resin film prepared by imidizing a polyamic acid-containing solution (eg, a polyamic acid solution) formed by solution polymerization of the above-described polyamic acid solution, that is, a polyamic acid composition.

Specifically, the transparent polyimide film includes a repeating unit represented by Formula 11 below.

[Formula 11]

In the above formula,

PI is a polyimide derived group formed by imidizing the result of polymerization of diamine and dianhydride,

R _a , R _b , R _c , R ₁₁ , R ₁₂ , R ₂₁ , R ₂₂ , R ₃₁ , R ₃₂ , o, p, and q are each as defined in Formula 1.

For example of the present invention, the PI may be more specifically expressed as a repeating unit represented by any one of the following Chemical Formulas 12 to 14.

[Formula 12]

[Formula 13]

[Formula 14]

In Chemical Formulas 12 to 14,

Ar ₁ is a divalent organic group derived from an alicyclic diamine or aromatic diamine, and a plurality of Ar ₁ are the same or different from each other,

Ar ₂ is a tetravalent organic group derived from an alicyclic dianhydride or aromatic dianhydride, wherein a plurality of Ar ₂ are the same or different from each other,

n is an integer of 1 or more, specifically, an integer between 1 and 10,000.

For a specific example of the present invention, the PI may be a polyimide-derived group represented by the following Chemical Formula 15 or 16, but is not limited thereto.

[Formula 15]

[Formula 16]

In the above formulas 15 to 16,

Ar ₁₁ to Ar ₁₅ are the same or different from each other, and each independently a divalent organic group derived from an alicyclic diamine or an aromatic diamine,

Ar ₂₁ to Ar ₂₅ are the same or different from each other, and each independently a tetravalent organic group derived from an alicyclic dianhydride or aromatic dianhydride,

n1 and n2 are each an integer of 1 to 10000, provided that n1+n2≥1,

m1 and m2 are each an integer of 1 to 10000, provided that m1+m2≥1.

In the above formulas 12 to 16, Ar ₁ (specifically, Ar ₁₁ to Ar ₁₅ ) derived from an alicyclic or aromatic diamine, and Ar ₂ (specifically, Ar ₂₁ to Ar derived from an alicyclic or aromatic dianhydride) ₂₅ ) are the same as the definitions in Chemical Formulas 5 to 9, and redundant description is omitted.

The polyimide resins represented by Formulas 11 to 16 according to the present invention are polymer materials containing imide rings. The form of the polyimide resin is not particularly limited, and may be, for example, a common random copolymer or block copolymer form known in the art. Specifically, the polyimide (PI) represented by Chemical Formula 12 may be in the form of a block (eg, A block) derived from diamine and a block (eg, B block) derived from dianhydride in AB form. . In addition, the polyimide (PI) represented by Chemical Formula 13 may be in the form of A-B-A, and the polyimide (PI) represented by Chemical Formula 14 may be in the form of B-A-B.

At this time, in the present invention, as a polyamic acid and a polyimide resin using the same, the structural formulas represented by the above-described formulas 4 to 16 are described in detail. However, the present invention is not limited to the above structural formulas, and as long as it includes a crosslink formed using the triamine represented by Chemical Formula 1 of the present invention, it is not particularly limited to the structure and shape of the polyamic acid and the polyimide resin, and various modifications This is possible.

For a preferred example of the present invention, the polyimide resin may be more specifically embodied as a compound represented by Formula 11a below.

[Formula 11a]

In the formula 11a,

PI is the same as defined in Formula 11 above,

R _a , R _b , R _c , R ₁₁ , R ₁₂ , R ₂₁ , R ₂₂ , R ₃₁ , R ₃₂ , o, p, and q are each as defined in Formula 1.

In addition, X may be an integer of 1 or more, and is not particularly limited to the upper limit. For example, it may be an integer between 1 and 10,000.

The polyimide film according to the present invention may be prepared by polymerizing a transparent polyamic acid solution (eg, a polyamic acid-containing solution) by exothermic solution polymerization according to a conventional method known in the art. For example, after coating (casting) the polyamic acid composition on a support, it may be prepared by inducing an imide ring reaction (Imidazation) for 0.5 to 8 hours while gradually raising the temperature in the range of 30 to 350°C. At this time, it is preferable to react under an inert atmosphere such as argon or nitrogen.

At this time, the coating method can be used without limitation conventional methods known in the art, for example, spin coating, dip coating, solvent casting, slot die coating And it may be made by at least one method selected from the group consisting of a spray coating. The colorless and transparent polyimide layer may be coated with a transparent polyamic acid composition one or more times so that the thickness becomes several tens of μm at several hundred nm.

In the method for producing a polyimide film according to the present invention, the imidization method applied to the step of imidizing the polymerized polyamic acid by casting it on a support is a thermal imidization method, a chemical imidization method, or a thermal imidization method and a chemical The imidization method can be used in combination.

The thermal imidization method is a method of casting a polyamic acid solution on a support and heating it slowly in a temperature range of 30 to 400°C while heating for 1 to 10 hours to obtain a polyimide film.

In addition, the chemical imidization method is a method of introducing a dehydrating agent represented by an acid anhydride such as acetic anhydride and an imidization catalyst represented by amines such as isoquinoline, β-picoline, and pyridine into a polyamic acid solution. When the thermal imidization method or the thermal imidation method is used in combination with the chemical imidization method, the heating conditions of the polyamic acid solution may be varied depending on the type of the polyamic acid solution, the thickness of the polyimide film to be produced, and the like.

When the production example of the polyimide film in the case where the thermal imidization method and the chemical imidation method are used in combination is described in more detail, a dehydrating agent and an imidation catalyst are added to a polyamic acid solution, cast onto a support, and then cast at 80 to 300°C. , Preferably by heating at 150 to 250° C. to activate the dehydrating agent and the imidation catalyst, and then partially cured and dried to obtain a polyimide film.

The thickness of the polyimide film of the present invention thus formed is not particularly limited, and may be appropriately adjusted depending on the field to be applied. For example, it may range from 10 to 150 μm, preferably 10 to 80 μm.

The transparent polyimide resin film according to the present invention may be applied to various fields, and specifically, may be used for a substrate such as a flexible display or a protective film. In order to be applied to such a display, it should basically have high transparency, low yellowness, and excellent mechanical characteristics at the same time. Specifically, the light transmittance of 550 nm is 10% or more at a film thickness of 10 μm, and the yellowness value of 550 nm is 7 or less. Is required. In addition, in order to secure reliability during the TFT deposition process, an adhesive force is required in which the polyimide on the support (glass substrate) does not peel off the glass substrate during the process.

Indeed, the polyimide film of the present invention prepared by imidizing the above-described triamine-containing polyamic acid composition may have low yellowness, high tensile strength and modulus of elasticity simultaneously while exhibiting high transparency. More specifically, the polyimide film has physical property conditions of (i) to (iv) below, such as (i) a light transmittance of wavelength 550 nm of 88% or more, and (ii) yellowness according to ASTM E313-73 standard (Yellow Index) may be 3.5 or less (based on 10 μm), (iii) tensile strength (MPa) according to ISO 527-3 standard may be 100 MPa or more, and (iv) elastic modulus (GPa) may be 3.5 GPa or more.

The transparent polyimide film of the present invention having the above-described physical properties can be particularly usefully applied to fields where high transparency and mechanical properties are required. For example, a display for an organic EL device (OLED), a display for a liquid crystal device, a TFT substrate, a flexible printed circuit board, a flexible OLED surface lighting substrate, a substrate for a flexible display, such as a substrate material for electronic paper, and/ Or it can be used as a protective film. However, it is not limited thereto.

Hereinafter, the present invention will be described in more detail through specific examples. The following examples are only examples for helping the understanding of the present invention, and the scope of the present invention is not limited thereto.

[Example 1]

1-1. Preparation of polyamic acid composition

After filling a 500 ml 3-neck round bottom flask with 204.917 g of N,N-dimethylacetamide (N,N-Dimethylacetamide, hereinafter referred to as DMAc), the temperature of the reactor was raised to 50°C, and 2,2'-bis (Trifluoromethyl)-4,4'-diaminophenyl (2,2'-Bis(trifluoromethyl)-4,4'-Diaminobiphenyl, hereinafter referred to as TFDB) 15.0 g (95 mol%) and represented by the following formula 3a 1.488 g (5 mol%) of triamine was added, and the monomer was stirred for 1 hour to dissolve completely. Subsequently, 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (2,2-bis (3,4- dicarboxyphenyl) Hexa fluoropropane dianhydride, hereinafter referred to as 6FDA) and pyromellitic Diane hydride (Pyromellitic dianhydride, hereinafter referred to as PMDA) was sequentially added to 17.523 g (80 mol%) and 2.151 g (20 mol%), respectively, and then cooled to 30°C to dissolve.

[Formula 3a]

1-2. Preparation of transparent polyimide film

After coating the transparent polyamic acid solution on a glass plate for LCD using a bar coater, in a nitrogen atmosphere convection oven at 80°C for 30 minutes, at 150°C for 30 minutes, at 200°C for 1 hour, at 300°C 1 Drying and imidazation were performed while gradually raising the temperature step by step. Accordingly, a transparent polyimide film having an imidation ratio of 85% or more and a film thickness of 52 µm was prepared, and then the polyimide film was separated from the glass plate and taken.

[Example 2]

1-1. Preparation of polyamic acid composition

Under the same conditions as in Example 1, after filling the round bottom flask with 220.478 g of DMAc, the temperature of the reactor was raised to 50° C. to give 15.0 g (90 mol%) of TFDB and 3.141 g (10 mol%) of triamine of Formula 3a. Was added and the monomer was stirred for 1 hour to dissolve completely. Subsequently, 18.497 g (80 mol%) of 6FDA, and 2.270 g (20 mol%) of PMDA were sequentially added, followed by cooling to 30°C to dissolve.

1-2. Preparation of transparent polyimide film

The colorless and transparent polyimide film production process was performed in the same manner as in Example 1.

[Comparative Example 1]

1-1. Preparation of polyamic acid composition

Under the same conditions as in Example 1, after filling the round bottom flask with 190.913 g of DMAc, the temperature of the reactor was raised to 50° C., 15.0 g (100 mol%) of TFDB was added, and the monomer was stirred for 1 hour to completely dissolve. Ordered. Subsequently, 16.647 g (80 mol%) of 6FDA and 2.043 g (20 mol%) of PMDA were sequentially added, followed by cooling to 30°C to dissolve.

1-2. Preparation of transparent polyimide film

The colorless and transparent polyimide film production process was performed in the same manner as in Example 1.

[Example 3]

1-1. Preparation of polyamic acid composition

Under the same conditions as in Example 1, after filling the round bottom flask with 192.403 g of DMAc, the temperature of the reactor was raised to 50° C., and 15.0 g (95 mol%) of TFDB and 1.488 g (5 mol%) of triamine of Formula 3a were obtained. Was added and the monomer was stirred for 1 hour to dissolve completely. Then, 3,3',4,4'-biphenyltetracarboxylic dianhydride (3,3',4,4'-Biphenyltetracarboxylic dianhydride, hereinafter referred to as BPDA) 8.704g (60mol%), and 8.762 g (40 mol%) of 6FDA were added sequentially, followed by cooling to 30°C to dissolve.

1-2. Preparation of transparent polyimide film

The colorless and transparent polyimide film production process was performed in the same manner as in Example 1.

[Example 4]

1-1. Preparation of polyamic acid composition

Under the same conditions as in Example 1, after filling the round bottom flask with 207.268 g of DMAc, the temperature of the reactor was raised to 50° C. to give 15.0 g (90 mol%) of TFDB and 3.141 g (10 mol%) of triamine of Formula 3a. Was added and the monomer was stirred for 1 hour to dissolve completely. Subsequently, 9.188 g (60 mol%) of BPDA and 9.248 g (40 mol%) of 6FDA were sequentially added, followed by cooling to 30°C to dissolve.

1-2. Preparation of transparent polyimide film

The colorless and transparent polyimide film production process was performed in the same manner as in Example 1.

[Comparative Example 2]

1-1. Preparation of polyamic acid composition

Under the same conditions as in Example 1, after filling the round bottom flask with 179.024 g of DMAc, the temperature of the reactor was raised to 50° C., 15.0 g (100 mol%) of TFDB was added, and the monomer was stirred for 1 hour to completely dissolve. Ordered. Subsequently, 8.269 g (60 mol%) of BPDA, and 8.324 g (40 mol%) of 6FDA were sequentially added, followed by cooling to 30°C to dissolve.

1-2. Preparation of transparent polyimide film

The colorless and transparent polyimide film production process was performed in the same manner as in Example 1.

[Example 5]

1-1. Preparation of polyamic acid composition

Under the same conditions as in Example 1, after filling the round bottom flask with 179.744 g of DMAc, the temperature of the reactor was raised to 50° C., and 2,2'-bis(trifluoromethyl)-4,4'-diamino 15.0 g (95 mol%) of diphenyl ether (2,2'-Bis(trifluoromethyl)-4,4'-diamin odiphenyl ether, hereinafter referred to as 6FODA) and 1.417 g (5 mol%) of triamine of formula 3a are added, The monomer was stirred for 1 hour to dissolve completely. Then cyclobutane-1,2,3,4-tetracarboxylic dianhydride (Cyclobutane-1,2,3,4-tetracarboxylic dianhydride, hereinafter referred to as CBDA) 5.526 g (60 mol%), and 4,4 9.777 g (40 mol%) of'-bisphenol-A dianhydride (4,4'-Bisphenol A dianhydride, hereinafter referred to as BPADA) were sequentially added, followed by cooling to 30°C to dissolve.

1-2. Preparation of transparent polyimide film

The colorless and transparent polyimide film production process was performed in the same manner as in Example 1.

[Example 6]

1-1. Preparation of polyamic acid composition

Under the same conditions as in Example 1, after filling the round bottom flask with 193.482 g of DMAc, the temperature of the reactor was raised to 50° C. to give 15.0 g (90 mol%) of 6FODA and 2.991 g (10 mol%) of triamine of Formula 3a. Was added and the monomer was stirred for 1 hour to dissolve completely. Subsequently, 5.833 g (60 mol%) of CBDA and 10.320 g (40 mol%) of BPADA were sequentially added, followed by cooling to 30°C to dissolve.

1-2. Preparation of transparent polyimide film

The colorless and transparent polyimide film production process was performed in the same manner as in Example 1.

[Comparative Example 3]

1-1. Preparation of polyamic acid composition

Under the same conditions as in Example 1, after filling the round bottom flask with 167.379 g of DMAc, the temperature of the reactor was increased to 50° C., 6FODA 15.0 g (100 mol%) was added, and the monomer was stirred for 1 hour to completely dissolve. Ordered. Subsequently, 5.249 g (60 mol%) of CBDA, and 9.288 g (40 mol%) of BPADA were sequentially added, followed by cooling to 30°C to dissolve.

1-2. Preparation of transparent polyimide film

The colorless and transparent polyimide film production process was performed in the same manner as in Example 1.

For reference, the compositions of the polyamic acid compositions prepared in Examples 1 to 6 and Comparative Examples 1 to 3 herein are shown in Table 1 below. At this time, mol% represents the molar ratio of each monomer in all of diamine, triamine, and dianhydride.

division	Diamine (mol%)	Triamine (mol%)	Diane hydride (mol%)
Example 1	TFDB(95)	Formula 3a (5)	6FDA(80)	PMDA(20)
Example 2	TFDB(90)	Formula 3a (10)	6FDA(80)	PMDA(20)
Example 3	TFDB(95)	Formula 3a (5)	BPDA(60)	6FDA(40)
Example 4	TFDB(90)	Formula 3a (10)	BPDA(60)	6FDA(40)
Example 5	6FODA(95)	Formula 3a (5)	CBDA(60)	BPADA(40)
Example 6	6FODA(90)	Formula 3a (10)	CBDA(60)	BPADA(40)
Comparative Example 1	TFDB(100)	-	6FDA(80)	PMDA(20)
Comparative Example 2	TFDB(100)	-	BPDA(60)	6FDA(40)
Comparative Example 3	6FODA(100)	-	CBDA(60)	BPADA(40)

[Physical property evaluation]

The properties of the polyimide films prepared in Examples 1 to 6 and Comparative Examples 1 to 3 were evaluated in the following manner, and the results are shown in Table 2 below.

<Method for evaluating physical properties>

(1) Measurement of light transmittance

It was measured using a UV-Vis NIR Spectrophotometer (Shimadzu, model name: UV-3150) at a wavelength of 550 nm.

(2) Yellowness measurement

The yellowness was measured by ASTM E313-73 standard using a spectrophotometer (Konica Minolta, model name: CM-3700d).

(3) Measurement of tensile strength and modulus of elasticity

Tensile strength (MPa) and modulus of elasticity (GPa) were measured in accordance with ISO 527-3 using UTM (Instron, model name: 5942).

division	Permeability (%)	Yellowness	Elastic modulus (Gpa)	Tensile strength (Mpa)
Example 1	88	3.2	3.8	114
Example 2	89	3.1	3.9	120
Example 3	89	2.9	4.0	118
Example 4	90	2.8	4.2	125
Example 5	90	3.0	3.6	110
Example 6	90	2.9	3.8	113
Comparative Example 1	86	3.9	3.3	93
Comparative Example 2	87	3.6	3.4	96
Comparative Example 3	87	3.7	3.2	92

According to the results of Table 2, the colorless and transparent polyimide film of the present invention containing triamine is superior in terms of light transmittance, yellowness, modulus of elasticity and tensile strength compared to Comparative Examples 1 to 3 without triamine. It was found to have. Specifically, in the present invention, as the triamine is included, a synergistic effect was exhibited in terms of yellowness and mechanical properties of the transparent polyimide film, and as the amount of triamine added increased, the yellowness significantly decreased, and the modulus and tensile strength were significantly It showed increasing results.

Based on the above results, the polyamic acid composition of the present invention was confirmed to be applicable to a flexible display (Flexible Display) substrate and a protective film.

Claims (16)

1. At least one diamine;

   At least one dianhydride; And

   A polyamic acid composition comprising a triamine represented by Formula 1 below:

   [Formula 1]

   

   In Chemical Formula 1,

   A ₁ is a C ₆ ~ C ₃₀ aromatic or C ₅ ~ C ₃₀ alicyclic organic group, the aromatic and alicyclic organic groups are each independently a monocyclic ring, or at least two rings are directly or through a bridge structure ,

   Y ₁ to Y ₃ are the same as or different from each other, each independently a single bond or -O-, -S-, -SO ₂ -, -COO-, -OCO-, C ₂ ~ C ₃₀ alkenyl group, C ₄ ~ C _{30 It} is selected from the group consisting of a cycloalkylene group and C ₆ ~ C ₃₀ arylene group,

   B ₁ to B ₃ are the same as or different from each other, and each independently a C ₆ to C ₃₀ aromatic or C ₅ to C ₃₀ alicyclic organic group, and the aromatic and alicyclic organic groups are each independently a monocyclic ring, or At least two rings are connected directly or through a crosslinked structure,

   R _a , R _b and R _c are the same as or different from each other, and each independently selected from the group consisting of hydrogen, halogen, cyano group, nitro group, C ₁ to C ₄₀ alkyl group, and -CF ₃ ,

   o, p and q are each independently an integer from 0 to 4,

   R ₁₁ , R ₁₂ , R ₂₁ , R ₂₂ , R ₃₁ and R ₃₂ are the same as or different from each other, and each independently hydrogen, halogen, cyano group, nitro group, C ₁ to C ₄₀ alkyl group, and -CF ₃ Is selected from the group consisting of,

   In the A ₁ , Y ₁ ~ Y ₃ , B ₁ ~ B ₃ , R _a ~ R _c , R ₁₁ , R ₁₂ , R ₂₁ , R ₂₂ , R ₃₁ and R ₃₂ , each hydrogen is independently halogen and -CF ₃ It may be substituted with one or more substituents selected from the group consisting of.
2. According to claim 1,

   The compound of Formula 1 is a polyamic acid composition represented by Formula 2 below:

   [Formula 2]

   

   In the above formula,

   R _a , R _b , R _c , R ₁₁ , R ₁₂ , R ₂₁ , R ₂₂ , R ₃₁ , R ₃₂ , o, p, and q are each as defined in claim 1.
3. According to claim 1,

   The compound of Formula 1 is a polyamic acid composition represented by Formula 3 below:

   [Formula 3]

   

   In the above formula,

   R ₁₁ , R ₁₂ , R ₂₁ , R ₂₂ , R ₃₁ , R ₃₂ , o, p, and q are each as defined in claim 1.
4. According to claim 1,

   The content of the triamine represented by the formula (1) is a polyamic acid composition of 1 to 20 mol% based on 100 mol% of the total amine combined with the diamine and triamine.
5. According to claim 1,

   The content of the triamine represented by Chemical Formula 1 is 0.1 to 20 parts by weight based on the total weight of the polyamic acid composition.
6. According to claim 1,

   The polyamic acid composition in which the ratio (a/b) of the number of moles of the total amine (a) combined with the diamine and the triamine to the dianhydride (b) ranges from 0.7 to 1.3.
7. According to claim 1,

   The at least one diamine is oxydianiline (ODA), 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (2,2'-TFDB), 2,2'-Bis(trifluoromethyl)-4,3'-diaminobiphenyl(2,2'-Bis(trifluoromethyl)-4,3'-Diaminobiphenyl),2,2'-bis (trifluoromethyl)- 5,5'-diaminobiphenyl (2,2'-Bis(trifluoromethyl) -5,5'-Diaminobiphenyl), 2,2'-bis(trifluoromethyl)-4,4'-diaminophenyl ether (2,2'-Bis (trifluoromethyl)-4,4'-diaminodiphenyl ether, 6-FODA), bis aminohydroxy phenyl hexafluoropropane (DBOH), bis amino phenoxy phenyl hexafluoropropane (4BDAF), Bis amino phenoxy phenylpropane (6HMDA), bis aminophenoxy diphenylsulfone (DBSDA), bis (4-aminophenyl) sulfone (4,4'-DDS), bis (3-aminophenyl) sulfone (3,3) One selected from the group consisting of'-DDS), sulfonyldiphthalanhydride (SO ₂ DPA), and 4,4'-oxydianiline (4,4'-ODA), bis(carboxyphenyl) dimethylsilane The above polyamic acid composition.
8. According to claim 1,

   The at least one dianhydride is pyromellitic dianhydride (PMDA), biphenyltetracarboxylic dianhydride (BPDA), 2,2-bis(3,4-dicarboxyphenyl)hexafluoro. Propane dianhydride (2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydrid, 6-FDA), 4,4'-Bisphenol A dianhydride (BPADA), 4- (Trifluoromethyl)pyromellitic dianhydride (4-TFPMDA), cyclobutane tetracarboxylic dianhydride (CBDA), 1,2,3,4-cyclopentane tetra One selected from the group consisting of carboxylic dianhydrides (CPDA) and bicyclo[2,2,2]-7-octene-2,3,5,6-tetracarboxylic dianhydrides (BCDA) The above polyamic acid composition.
9. According to claim 1,

   The composition comprises m-cresol, N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAc), dimethylsulfoxide (DMSO), acetone, diethyl acetate, dimethyl phthalate ( DMP), a polyamic acid composition comprising at least one solvent selected from the group consisting of tetrahydrofuran (THF), chloroform, and γ-butyrolactone.
10. Polyamic acid comprising a repeating unit represented by the following formula (4).

    [Formula 4]

    

    In the above formula,

    PAA is a polyamic acid or derivative thereof derived from the reaction of diamine and dianhydride,

    A ₁ is a C ₆ ~ C ₃₀ aromatic or C ₅ ~ C ₃₀ alicyclic organic group, the aromatic and alicyclic organic groups are each independently a monocyclic ring, or at least two rings are directly or through a bridge structure ,

    Y ₁ to Y ₃ are the same as or different from each other, each independently a single bond or -O-, -S-, -SO ₂ -, -COO-, -OCO-, C ₂ ~ C ₃₀ alkenyl group, C ₄ ~ C _{30 It} is selected from the group consisting of a cycloalkylene group and C ₆ ~ C ₃₀ arylene group,

    B ₁ to B ₃ are the same as or different from each other, and each independently a C ₆ to C ₃₀ aromatic or C ₅ to C ₃₀ alicyclic organic group, and the aromatic and alicyclic organic groups are each independently a monocyclic ring, or At least two rings are connected directly or through a crosslinked structure,

    R _a , R _b and R _c are the same as or different from each other, and each independently selected from the group consisting of hydrogen, halogen, cyano group, nitro group, C ₁ to C ₄₀ alkyl group, and -CF ₃ ,

    o, p and q are each independently an integer from 0 to 4,

    R ₁₁ , R ₁₂ , R ₂₁ , R ₂₂ , R ₃₁ and R ₃₂ are the same as or different from each other, and each independently hydrogen, halogen, cyano group, nitro group, C ₁ to C ₄₀ alkyl group, and -CF ₃ Is selected from the group consisting of,

    In the A ₁ , Y ₁ ~ Y ₃ , B ₁ ~ B ₃ , R _a ~ R _c , R ₁₁ , R ₁₂ , R ₂₁ , R ₂₂ , R ₃₁ and R ₃₂ , each hydrogen is independently halogen and -CF ₃ It may be substituted with one or more substituents selected from the group consisting of.
11. The method of claim 10,

    The PAA is a polyamic acid containing a repeating unit represented by any one of the following Chemical Formulas 5 to 7:

    [Formula 5]

    

    [Formula 6]

    

    [Formula 7]

    

    In the above formula 5 to 7,

    Ar ₁ is a divalent organic group derived from an alicyclic diamine or aromatic diamine, and a plurality of Ar ₁ are the same or different from each other,

    Ar ₂ is a tetravalent organic group derived from an alicyclic dianhydride or aromatic dianhydride, wherein a plurality of Ar ₂ are the same or different from each other,

    n is an integer between 1 and 10000.
12. A transparent polyimide film formed by imidizing the polyamic acid composition of any one of claims 1 to 9.
13. The method of claim 12,

    The polyimide is a transparent polyimide film comprising a repeating unit represented by Formula 11 below:

    [Formula 11]

    

    In Chemical Formula 11,

    PI is a polyimide derived group formed by imidizing the result of polymerization of diamine and dianhydride,

    A ₁ , Y ₁ to Y ₃ , B ₁ to B ₃ , R _a , R _b , R _c , R ₁₁ , R ₁₂ , R ₂₁ , R ₂₂ , R ₃₁ , R ₃₂ , o, p, and q are respectively As defined in claim 1.
14. The method of claim 13,

    The PI is a transparent polyimide film comprising a repeating unit represented by any one of the following Chemical Formulas 12 to 14:

    [Formula 12]

    

    [Formula 13]

    

    [Formula 14]

    

    In Chemical Formulas 12 to 14,

    Ar ₁ is a divalent organic group derived from an alicyclic diamine or aromatic diamine, and a plurality of Ar ₁ are the same or different from each other,

    Ar ₂ is a tetravalent organic group derived from an alicyclic dianhydride or aromatic dianhydride, wherein a plurality of Ar ₂ are the same or different from each other,

    n is an integer between 1 and 10000.
15. The method of claim 12,

    Transparent polyimide films satisfying the following physical conditions (i) to (iv):

    (i) the light transmittance of wavelength 550nm is 88% or more,

    (ii) Yellow index according to ASTM E313-73 standard (Yellow Index) is 3.5 or less,

    (iii) Tensile strength (MPa) according to ISO 527-3 standard is 100 MPa or more,

    (iv) Elastic modulus (GPa) is more than 3.5 GPa.
16. The method of claim 12,

    Transparent polyimide film used as a substrate and protective film for flexible displays.