KR102268861B1 - Polyimide precursor composition and polyimide film prepared using same - Google Patents

Abstract

The present invention comprises a diamine having a DDS structure and an amine-modified methylphenyl silicon oligomer at both ends and a dianhydride including PMDA (pyromellitic dianhydride) and BPDA (biphenyltetracarboxylic dianhydride) as a polymerization component, and a polyi containing an organic solvent having a partition coefficient LogP of positive number. By providing the imide precursor composition, it is possible to provide a polyimide film having a low residual stress and a glass transition temperature of 390° C. or higher.

Description

A polyimide precursor composition and a polyimide film using the same {POLYIMIDE PRECURSOR COMPOSITION AND POLYIMIDE FILM PREPARED USING SAME}

The present invention relates to a high heat-resistant polyimide film and a polyimide precursor composition for producing the same.

Recently, in the display field, weight reduction and miniaturization of products are becoming important, and in the case of the currently used glass substrate, it is heavy, brittle, and has limitations in that continuous processing is difficult. Research is being actively conducted to apply it to mobile phones, notebook computers, and PDA's.

In particular, polyimide (PI) resin is easy to synthesize, can make a thin film, and does not require a crosslinking group for curing. Recently, due to the light weight and precision of electronic products, it is integrated into semiconductor materials such as LCD and PDP. Many studies are being conducted to use PI for a flexible display board having light and flexible properties.

A polyimide (PI) film is produced by filming the polyimide resin, and in general, the polyimide resin is prepared by solution polymerization of an aromatic dianhydride and an aromatic diamine or an aromatic diisocyanate to prepare a polyamic acid derivative solution, and then It is manufactured by coating a silicon wafer or glass, etc. and curing it by heat treatment.

Flexible devices with high-temperature processes require heat resistance at high temperatures. In particular, organic light emitting diode (OLED) devices using a low temperature polysilicon (LTPS) process may have a process temperature approaching 500°C. However, at such a temperature, thermal decomposition by hydrolysis is likely to occur even for polyimide having excellent heat resistance. Therefore, it is necessary to develop a polyimide film capable of exhibiting excellent chemical resistance and storage stability in which thermal decomposition by hydrolysis does not occur even in a high-temperature process for manufacturing a flexible device.

An object of the present invention is to provide a polyimide precursor composition for producing a polyimide film having high heat resistance.

Another problem to be solved by the present invention is to provide a polyimide film using the polyimide precursor composition.

The present invention also provides a flexible display including the polyimide film and a manufacturing process thereof.

In order to solve the problem of the present invention,

Diamine and both terminal amine-modified methylphenylsilicone oligomer having the structure of Formula 1 below and dianhydride including BPDA (biphenyltetracarboxylic dianhydride) and PMDA (pyromellitic dianhydride) as a polymerization component, and an organic solvent having a partition coefficient Log P of 25 ° C. is positive. It provides a polyimide precursor composition comprising.

[Formula 1]

According to one embodiment, both terminal amine-modified methylphenyl silicon may have a structure of the following formula (2).

[Formula 2]

In Formula 2,

R is an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 24 carbon atoms,

p and q are mole fractions, and when p+q=100, p is 70-90 and q is 10-30.

According to one embodiment, the amine-modified methylphenyl silicon oligomer at both terminals may be included in an amount of 10 to 20% by weight based on the total weight of the total polymerization component.

According to an embodiment, the solvent in which LogP is a positive number is N,N-diethylacetamide (N,N-diethylacetamide, DEAc), N,N-diethylformamide (N,N-diethylformamide, DEF), N- It may be at least one selected from ethylpyrrolidone (N-ethylpyrrolidone, NEP), dimethylpropionamide (DMPA), and diethylpropionamide (DEPA).

According to an embodiment, the biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA) may be included in a molar ratio of 50 to 60:50 to 40.

According to an embodiment, the polyimide precursor composition may include an adhesion promoter in an amount of 0.05 to 3 parts by weight based on 100 parts by weight of the total solid content.

According to an embodiment, the adhesion promoter may have a structure represented by the following Chemical Formula 5 or Chemical Formula 6.

[Formula 5]

[Formula 6]

In Formulas 5 and 6,

Q ₁ is a tetravalent organic group having 1 to 30 carbon atoms or _a tetravalent organic group represented by R a -LR _{b , wherein R a} and R _b are each independently an aliphatic group having 4 to 10 carbon atoms, an aromatic group having 6 to 24 carbon atoms. , a cyclic aliphatic having 3 to 24 carbon atoms, and L is a single bond, -O-, -CR'R"-, -C(=O)-, -C(=O)O-, -C( =O)NH-, -S-, -SO ₂ -, a phenylene group and a combination thereof, wherein R' and R" are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, and It is selected from the group consisting of a fluoroalkyl group having 1 to 10 carbon atoms,

Q ₂ is a divalent organic group having 1 to 30 carbon atoms or a divalent organic group represented by _{R c} -LR _{d , wherein R c} and R _d are each independently an aliphatic group having 4 to 10 carbon atoms and an aromatic group having 6 to 24 carbon atoms. , a cyclic aliphatic having 3 to 24 carbon atoms, and L is a single bond, -O-, -CR'R"-, -C(=O)-, -C(=O)O-, -C( =O)NH-, -S-, -SO ₂ -, a phenylene group and a combination thereof, wherein R' and R" are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, and It is selected from the group consisting of a fluoroalkyl group having 1 to 10 carbon atoms,

R ₁ and R ₃ are each independently an alkyl group having 1 to 5 carbon atoms,

R ₂ and R ₄ are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms,

a and b are each independently an integer of 1 to 3.

The present invention also provides a polyimide film prepared from the polyimide precursor composition.

According to one embodiment, the polyimide film may have a glass transition temperature of 390° C. or higher.

According to an embodiment, the haze of the polyimide film may be 1 or less.

According to an embodiment, the thickness direction retardation of the polyimide film may be 100 nm or less.

In order to solve another object of the present invention, there is provided a flexible device including the polyimide film as a substrate.

The present invention also

applying the polyimide precursor composition onto a carrier substrate;

forming a polyimide film by heating the polyimide precursor composition to imidize the polyamic acid;

forming a device on the polyimide film; and

It provides a manufacturing process of a flexible device comprising the step of peeling the polyimide film formed with the element from the carrier substrate.

According to an embodiment, the manufacturing process may include a low-temperature polysilicon (LTPS) process, an ITO process, or an oxide process.

The present invention includes an organic solvent having a diamine having a DDS structure and an amine-modified methylphenyl silicone oligomer at both ends and a dianhydride including PMDA (pyromellitic dianhydride) and BPDA (biphenyltetracarboxylic dianhydride) as a polymerization component, and having a partition coefficient LogP of 25° C. is positive. By providing a polyimide precursor composition, it is possible to provide a polyimide film having a low residual stress and a glass transition temperature of 390° C. or higher.

1 shows a comparison of the white turbidity according to the PDMS content in a polyamic acid solution containing NMP and DEAc polymerization solvent, respectively.
Figures 2a and 2b is a photograph confirming the cloudiness phenomenon after spin-coating the polyamic acid solution of Examples and Comparative Examples.

Since the present invention can apply various transformations and can have various embodiments, specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. In describing the present invention, if it is determined that a detailed description of a related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

All compounds or organic groups in the present specification may be substituted or unsubstituted unless otherwise specified. Here, 'substituted' means that at least one hydrogen contained in the compound or organic group is a halogen atom, an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group, a cycloalkyl group having 3 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, or a hydroxyl group. , means substituted with a substituent selected from the group consisting of an alkoxy group having 1 to 10 carbon atoms, a carboxylic acid group, an aldehyde group, an epoxy group, a cyano group, a nitro group, an amino group, a sulfonic acid group, and derivatives thereof.

The present invention, a diamine and both terminal amine-modified methylphenyl silicone oligomer having the structure of Formula 1 below, and a dianhydride including PMDA (pyromellitic dianhydride) and BPDA (biphenyltetracarboxylic dianhydride) as a polymerization component, and 25 ℃ partition coefficient LogP is a positive number Provided is a polyimide precursor composition comprising an organic solvent.

[Formula 1]

The both-terminal amine-modified methylphenylsilicone oligomer may have the following structure.

[Formula 2]

In Formula 2,

R is an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 24 carbon atoms,

p and q are mole fractions, and when p+q=100, p is 70-90 and q is 10-30.

In addition, the present invention provides a polyimide film prepared from the polyimide precursor composition.

The compound represented by the above formula (1) is, for example, 4,4-(diaminodiphenyl)sulfone (hereinafter, 4,4-DDS), 3,4-(diaminodiphenyl)sulfone (3,4-DDS) and 3,3-(diaminodiphenyl)sulfone (3,3-DDS).

In general, the residual stress can be reduced by inserting methylphenylsilicone oligomer (also called PDMS) or polysiloxane into the structure of the polyimide, but due to the low heat resistance of the methylphenylsilicone oligomer, the glass transition temperature (Tg) of the polyimide film containing it There may be a problem of deterioration.

The present invention, together with DDS (diaminodiphenyl sulfone) having the structure of Formula 1, amine-modified methylphenyl silicon oligomer at both ends and BPDA, by polymerizing a polymerization component containing a dianhydride including PMDA 25 ℃ Log P by polymerizing in an organic solvent that is positive , it is possible to provide a polyimide film having a Tg of 390° C. or higher despite including a methylphenylsilicone oligomer.

According to one embodiment, the present invention may include 10 to 20% by weight of the amine-modified methylphenylsilicon oligomer at both ends based on the total weight of the total polymerization component, preferably 18% by weight or less. When both terminal amine-modified methylphenylsilicone oligomer is 10 wt% or more, the effect of reducing residual stress may be increased, and in a composition higher than 20 wt%, Tg may be lower than 390°C, thereby reducing heat resistance. In addition, cloudiness (haze) of the polyimide precursor composition may not occur within the above range.

In the present invention, Tg can be maintained at 390° C. or higher despite including up to 20% by weight of the methylphenylsilicone oligomer with respect to the total polymerization component. Accordingly, while maintaining the glass transition temperature at 390° C. or higher, the effect of reducing the residual stress due to the methylphenyl silicon oligomer structure can also be obtained.

When the amine-modified methylphenyl silicone oligomer at both ends is added excessively relative to the total weight of the polymer, mechanical properties such as the modulus of polyimide may be deteriorated, and the film strength may decrease, resulting in physical damage such as tearing of the film during the process. damage may occur. In addition, when both terminal amine-modified methylphenylsilicone oligomers are excessively added, Tg derived from the polymer having the siloxane structure may appear, and from this, Tg appears at a low process temperature of 350° C. or less, and 350° C. or higher. During the inorganic film deposition process, wrinkles may occur on the film surface due to the flow of polymer, which may lead to cracking of the inorganic film.

The molecular weight of the both-terminal amine-modified methylphenyl silicone oligomer may be 4000 g/mol or more, where the molecular weight means a weight average molecular weight, and the molecular weight is calculated using NMR analysis or acid-base titration. A method of calculating the amine equivalent can be used. .

When the molecular weight of the both-terminal amine-modified methylphenylsilicone oligomer is less than 4000 g/mol, heat resistance may decrease, for example, the glass transition temperature (Tg) of the prepared polyimide may decrease, or the coefficient of thermal expansion may increase excessively. can

According to one embodiment, both terminal amine-modified methylphenylsilicone oligomer may be included in 1 to 20 mol% of the total diamine, preferably 1 to 10 mol%.

According to the present invention, since the size of the methylphenylsilicon oligomer domains distributed in the polyimide matrix has a nanosize, for example, 1 nm to 50 nm, or 5 nm to 40 nm, or 10 nm to 30 nm, and has a continuous phase, heat resistance and mechanical properties are maintained. while minimizing residual stress. In the case of not having such a continuous phase, there may be an effect of reducing residual stress, but heat resistance and mechanical properties are remarkably reduced, making it difficult to use in the process.

Here, the domain of the methylphenylsilicone oligomer refers to a region in which a polymer having a methylphenylsilicone oligomer structure is distributed, and its size refers to the diameter of a circle surrounding the region.

It is preferable that the moieties (domains) including the methylphenylsilicon oligomer structure are connected in a continuous phase in the polyimide matrix, where the continuous phase means a shape in which nano-sized domains are uniformly distributed.

Therefore, in the present invention, despite being a methylphenylsilicone oligomer having a high molecular weight, it can be uniformly distributed without phase separation in the polyimide matrix, so that it is possible to obtain a polyimide having more transparent properties due to reduced haze properties, as well as methylphenylsilicone. Since the oligomer structure exists in a continuous phase, it is possible to more efficiently improve the mechanical strength and stress relief effect of polyimide. From these properties, the composition according to the present invention can provide a flat polyimide film by reducing not only thermal properties and optical properties, but also warping of the substrate after coating-curing.

According to the present invention, by inserting the methylphenylsilicone oligomer structure into the polyimide structure, the modulus strength of the polyimide can be appropriately improved and stress caused by an external force can also be alleviated. At this time, the polyimide including the methylphenylsilicone oligomer structure may exhibit polarity, and phase separation may occur due to a difference in polarity from the polyimide structure not including the siloxane structure, which causes the siloxane structure to be non-uniform throughout the polyimide structure. can be distributed. In this case, it is difficult to exhibit the effect of improving physical properties such as strength improvement and stress relief effect of the polyimide by the siloxane structure, and haze may increase due to phase separation, thereby reducing the transparency of the film. In particular, when the diamine having a siloxane structure has a high molecular weight, the polarity of the polyimide prepared therefrom appears more clearly, and phase separation between the polyimides may appear more clearly. In this case, when siloxane diamine having a low molecular weight structure is used, a large amount must be added in order to exhibit effects such as stress relief, which may cause problems in the process such as generation of Tg at a low temperature. Due to this, the physical properties of the polyimide film may be deteriorated. Accordingly, when siloxane diamine having a high molecular weight is added, a relaxation segment can be formed in a large amount in the molecule, and thus, a stress relief effect can be effectively exhibited even with a small amount compared to adding a low molecular weight. Therefore, in the present invention, by using the diamine compound having a siloxane structure having a high molecular weight, it can be more evenly distributed on the polyimide matrix without phase separation.

In the present invention, as an organic solvent for polymerizing the polymerization component, a solvent having a partition coefficient LogP of 25° C. is positive. In the organic solvent in which LogP is negative, the Tg decreases to less than 390° C. when the content of the methylphenylsilicone oligomer is 10% by weight or more, whereas in the present invention, as an organic solvent having a positive LogP is used, the methylphenylsilicone oligomer is 10 to 20% by weight Tg can be maintained at 390°C or higher even in the included composition.

In addition, the organic solvent having a positive partition coefficient as described above reduces the cloudiness caused by phase separation due to the difference in polarity between the flexible polyimide repeating structure and the polyimide structure including the siloxane structure such as methylphenylsilicone oligomer. can Conventionally, two types of organic solvents have been used to solve the phase separation, but the use of the organic solvent as described above can reduce cloudiness, and thus a more transparent polyimide film can be manufactured.

In order to solve the above problem, there is also a method of using a mixture of a polar solvent and a non-polar solvent, but in the case of a polar solvent, volatility tends to be high, and thus problems such as volatilization in advance may occur during the manufacturing process, In addition to problems such as a decrease in the reproducibility of the polyimide film, it may not be possible to completely improve the phase separation problem, so that the haze of the prepared polyimide film may increase and thus transparency may decrease. More specifically, by using a solvent having a structure in which the molecules of the solvent have amphiphilic properties, it is possible not only to solve the problem in the process of using a polar solvent, but also to use one type of solvent due to the molecular structure having amphiphilic properties. Even if only a solvent is used, the polyimide can be evenly distributed, so it is very suitable for solving problems caused by phase separation, thereby providing a polyimide with remarkably improved haze properties.

When the partition coefficient value is positive, it means that the polarity of the solvent is hydrophobic. According to the study of the present inventors, when the polyimide precursor composition is prepared using a specific solvent having a positive partition coefficient value, it can be seen that the edgeback phenomenon is improved. there was. In addition, the present invention can control the edge-back phenomenon of the solution without using an additive that controls the surface tension of the material and the smoothness of the coating film, such as a leveling agent, by using a solvent having a positive Log P as described above, This not only eliminates quality and process problems such as low molecular weight in the final product because no additional additives such as additives are used, but also has the effect of more efficiently forming a polyimide film having uniform properties. there is

For example, in the process of coating the polyimide precursor composition on a glass substrate, an edge-back phenomenon may occur due to the shrinkage of the coating layer during curing or under the conditions of leaving the coating solution under humidity conditions. The edge-back phenomenon of such a coating solution may cause a deviation in the thickness of the film, thereby causing the film to break due to the lack of flex resistance of the film or the edges to be crushed during cutting, resulting in poor workability in the process and lowering yield. Problems can arise.

In addition, when a fine foreign material having a polarity is introduced into the polyimide precursor composition applied on the substrate, in the polyimide precursor composition containing a polar solvent having a negative Log P, the position of the foreign material is based on the polarity of the foreign material. However, if a hydrophobic solvent with a positive Log P is used, the occurrence of thickness changes due to cracks in the coating is reduced or suppressed even when microscopic foreign substances with polarity are introduced. can be

Specifically, the polyimide precursor composition including the solvent in which Log P is a positive number may have an edge back ratio defined by Equation 1 below from 0% to 0.1% or less.

[Equation 1]

Edge whiteness (%) = [(A-B)/A]Х100

In the above formula 1,

A: the area in a state in which the polyimide precursor composition is completely coated on the substrate (100mmХ100mm),

B: The area after the edge-back phenomenon occurs from the edge end of the substrate coated with the polyimide precursor composition or the PI film.

The edge back phenomenon of the polyimide precursor composition and the film may occur within 30 minutes after coating the polyimide precursor composition solution, and in particular, the edge may be thickened by starting to roll in from the edge.

After coating the polyimide precursor composition according to the present invention on a substrate, the coated resin composition solution has an edge back rate of 0.1 after leaving it in a humidity condition for 10 minutes or more, for example, 10 minutes or more, for example, 40 minutes or more. % or less, for example, at a temperature of 20 to 30°C, a humidity condition of 40% or more, more specifically a humidity condition in the range of 40% to 80%, that is, 40%, 50%, 60%, 70% , at each humidity condition of 80%, for example, even after being left for 10 to 50 minutes at a humidity condition of 50%, it can exhibit a very small edge back rate of 0.1% or less, preferably 0.05%, more preferably almost An edge white ratio close to 0% may be exhibited.

The edge back rate as described above is maintained even after curing, for example, after coating the polyimide precursor composition on the substrate for 10 minutes or more, for example, at a temperature of 20 to 30° C., a humidity condition of 40% or more, more specifically Humidity conditions in the range of 40% to 80%, that is, 40%, 50%, 60%, 70%, 80% each humidity condition, for example, curing after leaving for 10 to 50 minutes at a humidity condition of 50% The edge back ratio of the polyimide film may be 0.1% or less, that is, almost no edge back phenomenon occurs even in the curing process by heat treatment, specifically, 0.05%, more preferably, an edge close to 0% percentage can be expressed.

The polyimide precursor composition according to the present invention can obtain a polyimide film having more uniform properties by solving such an edge back phenomenon, thereby further improving the yield of the manufacturing process.

In addition, when the density of the solvent according to the present invention is measured by the standard measurement method of ASTM D1475, it may be 1 g/cm ³ or less, and when the density has a value of 1 g/cm 3 or more, the relative viscosity may be increased, so that the efficiency in the process This can be reduced.

The solvent in which LogP is positive is, for example, N,N-diethylacetamide (N,N-diethylacetamide, DEAc), N,N-diethylformamide (N,N-diethylformamide, DEF), N-ethyl It may be at least one selected from pyrrolidone (N-ethylpyrrolidone, NEP), dimethylpropionamide (DMPA), and diethylpropionamide (DEPA).

The organic solvent may have a boiling point of 300° C. or less, and more specifically, a 25° C. partition coefficient LogP value of 0.01 to 3, or 0.01 to 2, or 0.1 to 2, of the organic solvent.

The partition coefficient can be calculated using the ACD/LogP module of the ACD/Percepta platform of ACD/Labs, and the ACD/LogP module uses the 2D structure of the molecule to implement an algorithm based on the QSPR (Quantitative Structure-Property Relationship) methodology. use it

According to an embodiment, the BPDA:PMDA may be included in a molar ratio of 40-60:60-40. The present invention may include BPDA in an amount of 40 to 60 mol% of the total dianhydride, and the mol% of BPDA may affect the properties of Tg and YI. For example, when the BPDA is included in an excess of 60 mol%, Tg may decrease, and when less than 40 mol%, yellowness (YI) may increase.

PMDA may be included in 60 to 40 mol% of the total dianhydride, and when the PMDA is included in an excess of 60 mol%, yellowness may increase, for example, it may exhibit a yellowness value greater than 8, and , when PMDA is included in less than 40 mol%, Tg may be lowered.

According to an embodiment, the thickness direction retardation (Rth) of the polyimide film may be 100 nm or less, preferably -100 to +100 nm, and more preferably 80 nm or less. When the content of PMDA is increased than 60 mol% and the content of BPDA is decreased than 40 mol%, the retardation in the thickness direction exhibits a value greater than 100 nm, thereby reducing optical isotropy.

In the polymerization of the polyamic acid, tetracarboxylic dianhydride may be further included in addition to BPDA and PMDA, and, for example, tetracarboxylic dianhydride including a tetravalent organic group selected from the following structures 3a to 3h is further included. can do.

[Formula 3a]

[Formula 3b]

[Formula 3c]

[Formula 3d]

[Formula 3e]

[Formula 3f]

[Formula 3g]

[Formula 3h]

In Formulas 3a to 3h, R ₁₁ to R ₂₄ are each independently a halogen atom selected from the group consisting of -F, -Cl, -Br and -I, a hydroxyl group (-OH), and a thiol group (-SH ), a nitro group (-NO ₂ ), a cyano group, an alkyl group having 1 to 10 carbon atoms, halogenoalkoxy having 1 to 4 carbon atoms, halogenoalkyl having 1 to 10 carbon atoms, and an aryl group having 6 to 20 carbon atoms. can,

wherein a1 is an integer from 0 to 2, a2 is an integer from 0 to 4, a3 is an integer from 0 to 8, a4 and a5 are each independently an integer from 0 to 3, and a7 and a8 are each independently from 0 to 3 may be integers, a10 and a12 are each independently an integer of 0 to 3, a11 is an integer of 0 to 4, a15 and a16 are each independently an integer of 0 to 4, a17 and a18 are each independently an integer of 0 to 4 and a6, a9, a13, a14, a19, a20 are each independently an integer of 0 to 3,

n is an integer from 1 to 3,

A11 to A16 are each independently a single bond, -O-, -CR'R"-, -C(=O)-, -C(=O)O-, -C(=O)NH-, -S- , -SO ₂ -, may be selected from the group consisting of a phenylene group, and combinations thereof, wherein R' and R" are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, and fluoro having 1 to 10 carbon atoms. It is selected from the group consisting of an alkyl group.

During polymerization of the polyamic acid, the diamine may further include other diamines in addition to the DDS and both terminal amine-modified methylphenylsilicone oligomers of Formula 1, for example, may further include a diamine having a structure as shown in Formula 4 below.

[Formula 4]

In Formula 4,

Wherein R ₃₁ , R ₃₂ are each independently a halogen atom selected from the group consisting of -F, -Cl, -Br and -I, a hydroxyl group (-OH), a thiol group (-SH), a nitro group (-NO ₂ ), a substituent selected from a cyano group, an alkyl group having 1 to 10 carbon atoms, a halogenoalkoxy having 1 to 4 carbon atoms, a halogenoalkyl having 1 to 10 carbon atoms, and an aryl group having 6 to 20 carbon atoms, preferably a halogen atom , may be a substituent selected from a halogenoalkyl group, an alkyl group, an aryl group, and a cyano group. For example, the halogen atom may be fluoro (-F), and the halogenoalkyl group is a fluoroalkyl group having 1 to 10 carbon atoms including a fluoro atom, and is a fluoromethyl group, perfluoroethyl group, trifluoro It may be selected from a methyl group, and the alkyl group may be selected from a methyl group, an ethyl group, a propyl group, an isopropyl group, a t-butyl group, a pentyl group, and a hexyl group, and the aryl group may be selected from a phenyl group and a naphthalenyl group. may be one, and more preferably a substituent including a fluoro atom such as a fluoro atom and a fluoroalkyl group.

Q is a single bond, -O-, -CR'R"-, -C(=O)-, -C(=O)O-, -C(=O)NH-, -S-, -SO ₂ - , may be selected from the group consisting of a phenylene group and combinations thereof, wherein R' and R" are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, and a fluoroalkyl group having 1 to 10 carbon atoms. will be chosen

In this case, the 'fluoro-based substituent' of the present invention means not only a 'fluoro atom substituent' but also a 'substituent containing a fluoro atom'.

The polyimide film composition may further include an adhesion promoter, and the adhesion promoter may be included in an amount of 0.05 to 3 parts by weight, preferably 0.05 to 2 parts by weight, based on 100 parts by weight of the total solid content.

According to an embodiment, the adhesion promoter may have a structure represented by the following Chemical Formula 5 or Chemical Formula 6.

[Formula 5]

[Formula 6]

In Formulas 5 and 6,

Q1 is a tetravalent organic group having 1 to 30 carbon atoms or _a tetravalent organic group represented by R a -LR _{b , wherein R a} and R _b are each independently an aliphatic having 4 to 10 carbon atoms, an aromatic having 6 to 24 carbon atoms, It is selected from cyclic aliphatic having 3 to 24 carbon atoms, and L is a single bond, -O-, -CR'R"-, -C(=O)-, -C(=O)O-, -C(= O) NH-, -S-, -SO ₂ -, a phenylene group, and a combination thereof, wherein R' and R" are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, and a carbon number 1 to 10 is selected from the group consisting of a fluoroalkyl group, more preferably L is -SO ₂ -, -CO-, -O-, C(CF ₃ ) ₂ It may be one selected from,

Q ₂ is a divalent organic group having 1 to 30 carbon atoms or a divalent organic group represented by _{R c} -LR _{d , wherein R c} and R _d are each independently an aliphatic group having 4 to 10 carbon atoms and an aromatic group having 6 to 24 carbon atoms. , a cyclic aliphatic having 3 to 24 carbon atoms, and L is a single bond, -O-, -CR'R"-, -C(=O)-, -C(=O)O-, -C( =O)NH-, -S-, -SO ₂ -, a phenylene group and a combination thereof, wherein R' and R" are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, and It is selected from the group consisting of a fluoroalkyl group having 1 to 10 carbon atoms,

R ₁ and R ₃ are each independently an alkyl group having 1 to 5 carbon atoms,

R ₂ and R ₄ are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, more preferably an ethyl group,

a and b are each independently an integer of 1 to 3.

For example, Q ₁ may be a tetravalent organic group selected from the following Chemical Formulas 5a to 5s, but is not limited thereto.

The adhesion promoter having the structure of Formula 5 can not only improve adhesion with the inorganic layer, but also has low reactivity with polyamic acid. When alkoxysilane-based additives such as ICTEOS and APTEOS, which are general adhesion-improving additives, are added, polya It is possible to reduce the increase in viscosity caused by the side reaction of the mixed acid and the additive, so storage stability at room temperature can be improved.

In Formula 6, Q ₂ may be a divalent organic group selected from Formulas 6a to 6s, but is not limited thereto.

Conventionally, high heat-resistant polyimide used as a flexible display substrate uses a method of coating and forming an adhesion promoter on glass to increase adhesion with a glass substrate on which an inorganic layer is deposited or glass used as a carrier substrate. of the adhesion promoter had a low limit in terms of economic feasibility because foreign matter was generated due to the application of the adhesion promoter or an additional coating process was required. In addition, even when the adhesion promoter is directly added to the polyimide resin precursor, there has been a problem in that the amino group forms a salt with the carboxylic acid of the polyamic acid and precipitates, thereby reducing the adhesion.

In addition, there is a prior art that can improve the adhesion by directly adding an adhesion promoter to the polyimide resin precursor, but it results in an increase in the retardation value in the thickness direction, so it can be used as an adhesion promoter, but the resulting polyimide There was a problem that may affect the physical properties of the film. This is because, in the prior art, an adhesion promoter made of an acid anhydride having two or more aromatic structures is generally used, and since a relatively rigid structure is used, a retardation phenomenon may appear in this part after curing.

In addition, when an adhesion promoter including a flexible structure such as ODPA (4,4'-oxydiphthalic anhydride) is used, the retardation value does not increase due to the flexibility of the structure, but the Tg tends to decrease.

According to a preferred embodiment, the adhesion promoter may have a fluorene skeleton. In this case, while maintaining the adhesion promotion effect as much as possible, free volume between molecules is generated due to the fluorene skeleton and isotropic because it does not affect the packing density. can show the characteristics of In addition, it is possible to provide a high heat-resistant isotropic polyimide film that does not affect the retardation value in the thickness direction and heat resistance, which are optical properties of a polyimide film having excellent heat resistance due to a structural feature containing a lot of aromatics.

That is, even when an adhesion promoter is mixed with the polyimide resin precursor, it does not precipitate, and the occurrence of foreign substances can be minimized, thereby providing excellent adhesion to the substrate, and retardation in the thickness direction, which is the optical property of the polyimide film made after coating and curing. It does not affect the isotropic polyimide film can be provided.

According to an embodiment of the present invention, the total content of tetracarboxylic dianhydride and the content of the diamine may be reacted in a molar ratio of 1:1.1 to 1.1:1, preferably, in order to improve reactivity and improve fairness, It is preferable that the total content of the tetracarboxylic dianhydride is reacted in excess compared to the diamine, or the content of the diamine is reacted in excess compared to the total content of the tetracarboxylic dianhydride.

According to an embodiment of the present invention, the molar ratio of the total content of the tetracarboxylic dianhydride and the content of diamine may be 1:0.99 to 0.99:1, or 1:0.98 to 0.98:1.

The method of reacting the tetracarboxylic dianhydride with diamine may be carried out according to a conventional polyimide precursor polymerization method such as solution polymerization. Specifically, it can be prepared by dissolving diamine in an organic solvent, and then adding tetracarboxylic dianhydride to the resulting mixed solution for polymerization.

The polymerization reaction may be carried out under an inert gas or nitrogen stream, and may be carried out under anhydrous conditions.

In addition, the reaction temperature during the polymerization reaction may be carried out at -20 to 80 ℃, preferably 0 to 80 ℃. When the reaction temperature is too high, the reactivity may increase and the molecular weight may increase, and the viscosity of the precursor composition may increase, which may be disadvantageous in terms of the process.

It is preferable to include the solid content in the polyamic acid solution prepared according to the above-described manufacturing method in an amount such that the composition has an appropriate viscosity in consideration of fairness such as applicability during the film forming process.

The polyimide precursor composition containing the polyamic acid may be in the form of a solution dissolved in an organic solvent, and in the case of having such a form, for example, when the polyimide precursor is synthesized in an organic solvent, the solution is the obtained reaction solution that It may be itself, or what diluted this reaction solution with another solvent may be sufficient. Moreover, when a polyimide precursor is obtained as solid powder, what was made to melt|dissolve this in an organic solvent and was made into a solution may be sufficient.

According to one embodiment, the content of the composition may be adjusted by adding an organic solvent so that the total content of the polyimide precursor is 8 to 25 wt%, preferably 10 to 25 wt%, more preferably 10 to 20 wt% % or less.

Alternatively, the polyimide precursor composition may be adjusted to have a viscosity of 2,000 cP or more, and the viscosity of the polyimide precursor composition is adjusted to have a viscosity of 10,000 cP or less, preferably 9,000 cP or less, more preferably 8,000 cP or less It is preferable to do When the viscosity of the polyimide precursor composition exceeds 10,000 cP, the efficiency of defoaming during processing of the polyimide film is lowered, so that not only the efficiency in the process but also the surface roughness of the prepared film is poor due to the generation of bubbles, resulting in electrical, optical, and mechanical properties. may be lowered.

In addition, the molecular weight of the polyimide according to the present invention may have a weight average molecular weight of 10,000 to 200,000 g/mol, or 20,000 to 100,000 g/mol, or 30,000 to 100,000 g/mol.

In addition, the molecular weight distribution (Mw/Mn) of the polyimide according to the present invention is preferably 1.1 to 2.5. When the weight average molecular weight or molecular weight distribution of the polyimide is out of the above range, it may be difficult to form a film, or there is a fear that the properties of the polyimide-based film such as transmittance, heat resistance and mechanical properties may be deteriorated.

Then, a transparent polyimide film can be prepared by imidizing the polyimide precursor obtained as a result of the polymerization reaction.

According to one embodiment, the polyimide precursor composition obtained as described above comprises:

applying the polyimide precursor composition on a substrate; and

A polyimide film may be manufactured through the step of heat-treating the applied polyimide precursor composition.

At this time, as the substrate, glass, metal substrate, or plastic substrate, etc. may be used without any particular limitation. Among them, the polyimide precursor has excellent thermal and chemical stability during imidization and curing processes, and is cured without a separate release agent treatment. A glass substrate that can be easily separated without damage to the polyimide-based film formed afterward may be desirable.

In addition, the coating process may be carried out according to a conventional coating method, specifically, a spin coating method, a bar coating method, a roll coating method, an air-knife method, a gravure method, a reverse roll method, a kiss roll method, a doctor blade method, A spray method, a dipping method, or a brushing method may be used. Among them, a continuous process is possible, and it may be more preferable to be carried out by a casting method that can increase the imidization rate of polyimide.

In addition, the polyimide precursor composition may be applied on the substrate in a thickness range such that the finally manufactured polyimide film has a thickness suitable for a display substrate.

Specifically, it may be applied in an amount so as to have a thickness of 10 to 30 μm. After the polyimide precursor composition is applied, a drying process for removing the solvent present in the polyimide precursor composition may be optionally further performed prior to the curing process.

The drying process may be carried out according to a conventional method, and specifically may be carried out at a temperature of 140 °C or less, or 80 °C to 140 °C. If the temperature at which the drying process is performed is less than 80° C., the drying process is prolonged, and when it exceeds 140° C., imidization proceeds rapidly, making it difficult to form a polyimide film having a uniform thickness.

Then, the polyimide precursor composition is applied to the substrate and heat-treated on an IR oven, a hot air oven or a hot plate, wherein the heat treatment temperature may be in the range of 300 to 500°C, preferably 320 to 480°C, It may proceed as a multi-step heat treatment within the temperature range. The heat treatment process may be carried out for 20 minutes to 70 minutes, preferably for about 20 minutes to 60 minutes.

Thereafter, the polyimide film can be produced by peeling the polyimide film formed on the substrate from the substrate according to a conventional method.

The polyimide film prepared as described above may have a modulus of 3 GPa or less, for example, 0.1 to 2.2 GPa, and an elongation of 20% or more. When the modulus (modulus of elasticity) is less than 0.1 GPa, the film has low rigidity and is easily broken by external impact. When the modulus of elasticity exceeds 3 GPa, the coverlay film has excellent rigidity but cannot secure sufficient flexibility. have.

In addition, the polyimide film according to the present invention may have excellent thermal stability according to temperature change, for example, the coefficient of thermal expansion after n+1 times of heating and cooling in a temperature range of 100°C to 350°C is -10 It may have a value of to 100 ppm/°C, preferably a value of -7 to 90 ppm/°C, and more preferably 80 ppm/°C or less (in this case, n is an integer greater than or equal to 0).

In addition, the polyimide film according to the present invention _{may exhibit optical isotropy by having a thickness direction retardation (R th} ) of -100 nm to +100 nm, preferably -80 nm to +80 nm, so that visibility can be improved. .

According to one embodiment, the residual stress of the polyimide film may be 40 MPa or less, preferably 32 MPa or less.

According to one embodiment, the polyimide film may have an adhesive strength of 5 gf/in or more to the carrier substrate, preferably 10 gf/in or more.

In addition, the present invention,

A polyimide precursor composition comprising an organic solvent containing diamine containing DDS (diaminodiphenyl sulfone), both terminal amine-modified methylphenyl silicon oligomer, and dianhydride containing PMDA and BPDA as polymerization components, and having a positive partition coefficient Log P, as a carrier substrate applying on top;

forming a polyimide film by heating the polyimide precursor composition to imidize the polyamic acid;

forming a device on the polyimide film; and

It provides a manufacturing process of a flexible device comprising the step of peeling the polyimide film formed with the element from the carrier substrate.

In particular, the manufacturing process of the flexible device may include a low temperature polysilicon (LTPS) process, an ITO process, or an oxide process.

For example, forming a barrier layer comprising _{SiO 2} on the polyimide film;

depositing an amorphous silicon (a-Si) thin film on the blocking layer;

a dehydrogenation annealing step of heat-treating the deposited a-Si thin film at a temperature of 450±50° C.; and

After the LTPS thin film manufacturing process including crystallizing the a-Si thin film with an excimer laser or the like, a flexible device including the LTPS layer can be obtained by peeling the polyimide film from the carrier substrate by laser peeling or the like.

The oxide thin film process may be heat treated at a lower temperature than a process using silicon, for example, the heat treatment temperature of the ITO TFT process may be 240°C±50°C, and the heat treatment temperature of the oxide TFT process is 350°C±50°C can be

Hereinafter, embodiments of the present invention will be described in detail so that those of ordinary skill in the art can easily carry out the present invention. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein.

<Example 1> BPDA-PMDA (6:4)/DDS-PDMS 6wt%/DEAc

After filling DEAc (N,N-diethylacetamide) in a reactor with a nitrogen stream flowing, 0.1509 mol of 4,4'-DDS (4,4'-diaminodiphenyl sulfone) was added at the same temperature while the temperature of the reactor was maintained at 25°C. was added to dissolve. After adding 0.0601 mol of PMDA (pyromellitic dianhydride) and 0.090 mol of BPDA (3,3',4,4'-biphenyltetracarboxylic dianhydride) to the DDS-added solution at the same temperature and stirring for 24 hours, both ends of amine-modified DMS- 0.0075 mol of DPS (diphenylsiloxane-dimethylsiloxane co-oligomer, molecular weight 4360 g/mol) was added and stirred at 80° C. for 4 hours. After that, the oil bath was removed, returned to room temperature, and a transparent polyamic acid solution was obtained.

<Examples 2 to 6> BPDA-PMDA (6:4)/DDS-PDMS/DEAc

A polyamic acid solution was prepared in the same manner as in Example 1, except that PDMS was added in the composition shown in Table 2 below.

<Examples 7 to 9> BPDA-PMDA (4:6) / DDS-PDMS / DEAc

A polyamic acid solution was prepared in the same manner as in Example 1, except that the composition of BPDA-PMDA was changed to 4:6 instead of 6:4, and the content of PDMS was changed.

<Comparative Example 1> BPDA-PMDA (6:4)/DDS-PDMS 15wt%/NMP

A polyamic acid solution was prepared in the same manner as in Example 1, except that NMP was used as a solvent and the PDMS content was 15 wt%.

<Experimental Example 1> Polyamic acid solution cloudiness comparison

When NMP and DEAc solvents were used for BPDA:PMDA(6eq.:4eq.)-DDS polymerization, respectively, the white turbidity (Hzae) of the polyamic acid solution according to the PDMS content was compared and shown in FIG. 1 .

As can be seen from FIG. 1 , when DEAc is used as a polymerization solvent, it can be seen that cloudiness does not occur even when the PDMS content is increased. Solvents having a positive LogP, such as DEAc, exhibit hydrophobic properties, and due to this, the ability to absorb moisture present inside and outside the solvent is low, and the surface tension is also low, so that the cloudiness of the polyamic acid solution due to moisture may be little or hardly appear. Therefore, it is possible to improve the haze of the polyamic acid solution only by using a solvent having a positive LogP without adding additional additives to control the cloudiness caused by moisture, etc., which reduces the haze of the polyimide film produced therefrom. By reducing it, it is possible to prepare a more transparent polyimide film.

<Experimental Example 2>

Each of the polyimide precursor solutions prepared in Examples 1 to 6 and Comparative Example 1 was spin-coated on a glass substrate. 2a and 2b are photographs confirming the cloudiness phenomenon after spin coating the precursor solutions prepared in Example 5 and Comparative Example 1, respectively. It can be seen that FIG. 2a shows little cloudiness, and FIG. 2b shows severe cloudiness.

The glass substrate coated with the polyimide precursor solution was placed in an oven and heated at a rate of 5° C./min, and the curing process was performed by maintaining at 80° C. for 30 minutes and at 400° C. for 30 minutes to prepare a polyimide film.

The physical properties of each film were measured and shown in Tables 1 and 2 below.

<Yellowness (YI)>

Yellowness (YI) was measured with Color Eye 7000A.

<Haze>

Haze was measured by a method according to ASTM D1003 using a Haze Meter HM-150.

<Transmittance>

Transmittance was measured for transmittance at wavelengths of 450 nm, 550 nm and 633 nm with a transmittance meter (model name HR-100, manufactured by Murakami Color Research Laboratory) in accordance with JIS K 7105.

<Thickness direction phase difference (R _th )>

The thickness direction retardation (Rth) was measured using Axoscan. After cutting the film to a certain size, measuring the thickness, and then measuring the retardation with Axoscan, the measured thickness was inputted while correcting the C-plate direction to compensate for the retardation value.

<Glass transition temperature (Tg) and coefficient of thermal expansion (CTE)>

After preparing the film in a size of 5 x 20 mm, the sample is loaded using an accessory. The length of the film actually measured was the same as 16 mm. After setting the film pulling force to 0.02N and performing the first temperature increase process at a temperature increase rate of 5 °C/min in a temperature range of 100 to 350 °C, a cooling rate of 4 °C/min in a temperature range of 350 to 100 °C After cooling, a second temperature increase process was performed in a temperature range of 100 to 450° C. at a temperature increase rate of 5° C./min, and the change in thermal expansion was measured by TMA (Q400 manufactured by TA).

At this time, the inflection point seen in the temperature increase section in the second temperature increase process was taken as Tg.

<Pyrolysis temperature (Td1%)>

The temperature when the weight reduction rate of the polymer was 1% in a nitrogen atmosphere was measured using TGA.

<Modulus (GPa), tensile strength (MPa), elongation (%)>

A film with a length of 5 mm X 50 mm and a thickness of 10 μm was stretched with a tensile tester (manufactured by Instron Co., Ltd.: Instron 3342) at a speed of 10 mm/min to measure modulus (GPa), tensile strength (MPa), and elongation (%).

<Residual stress and Bow value measurement>

A resin composition was applied by a spin coater (manufactured by Koyo Lindbergh) on a 6-inch silicon wafer with a thickness of 525 μm, which had been previously measured [warping amount] of the wafer using a residual stress measuring device (FLX2320, manufactured by TENCOR), and an oven was opened. A silicon wafer with a resin film of 10 μm in thickness after curing was prepared by heat curing at 250° C. for 30 min and 400° C. for 60 min under a nitrogen atmosphere. The amount of warpage of this wafer was measured by using the residual stress measuring apparatus described above in the above method, and it was expressed as a Real Bow value, and the residual stress generated between the silicon wafer and the resin film was measured.

Sample Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 polymer structure BPDA_6eq-PMDA_4eq-DDS PDMS content wt% 6 8 10 13 15 18 Sol. Con. wt% 20.8 20.7 21.8 24.8 24 22.8 Viscosity cps 3065 2978 4100 4081 2734 2841 Thickness um 9.89 10.1 10.2 9.78 10 10 YI 6.72 7.51 7.9 7.6 6.8 6.8 Haze 0.12 0.25 0.23 0.16 0.27 0.28 Rth nm @ 550 nm 102 84 74 64 60 53 Transmittance % 450 nm 82.9 82.2 78.1 83.4 83.0 83.7 550 nm 87.7 87.7 84.8 88.0 88.2 89.1 630 nm 88.8 88.8 86.4 89.0 89.4 90.2 CTE
100-350 ^o C

ppm/℃ 1 ^st
heating 41.5 38.1 45.8 38.9 37.8 37.9 1 ^st
cooling 68.2 65.8 67.6 63.0 66.5 60.2 Tg ^o C 400 400 400 395 393 391 Td1% 489 485 479 474 470 465 Weight loss (%) 350℃,
60min 0.0040 0.0115 0.0262 0.0339 0.0385 0.0397 Weight loss (%) 380℃,
60min 0.0698 0.0628 0.0750 0.1182 0.1426 0.1645 Modulus GPa 2.6 2.4 2.1 2.0 1.9 1.7 Tensile strength MPa 103 95 85.7 83 82 69 Strain % 21 20 20 29 28 28 Real Bow, um 38.8 36.4 29.9 27 24 21 Residual stress, MPa 38.6 35.5 31.1 27 24 21

In Table 1, it can be seen that the residual stress decreases as the content of PDMS increases in Examples 1 to 6, and despite the increase in the content of PDMS, the glass transition temperature can still be exhibited at 390° C. or higher.

Example 5 Comparative Example 1 BPDA:PMDA(6:4)-DDS PDMS wt.% 15 15 Solvent DEAc NMP Sol. Con. wt% 24 17 Viscosity cps 2734 2860 Thickness um 10 10 YI 6.8 7.3 Rth 60 31 Haze 0.27 1.2 Transmittance % 450 nm 83.0 81.3 550 nm 88.2 86.5 630 nm 89.4 87.6 CTE
100-350 ^o C
ppm/℃ 1 ^st heating 37.8 44.7 1 ^st cooling 66.5 62.2 Tg ℃ 393 388 Td 1% ℃ 465 469 Isothermal 350℃/60min 0.039 0.033 Isothermal 380℃/60min 0.143 0.152 Modulus Gpa 1.9 1.9 Tensile strength MPa 82 87 Strain % 28 27 Residual stress, Mpa 24 27 Bowing, um 24 26

As can be seen from Table 2, the polyimide film using NMP has a Tg lowered to 390° C. or less in the composition in which 15 wt% of PDMS is added, but the polyimide film of Example 5 has a PDMS of 15 wt% by using DEAc with a positive LogP. It can be seen that even under the condition of % or higher, a Tg value of 390°C or higher can still be exhibited.

As described above in detail a specific part of the present invention, for those of ordinary skill in the art, it is clear that this specific description is only a preferred embodiment, and the scope of the present invention is not limited thereby. something to do. Accordingly, the substantial scope of the present invention will be defined by the appended claims and their equivalents.

Claims (15)

Diamine and both terminal amine-modified methylphenylsilicone oligomer having the structure of Formula 1 below and dianhydride including BPDA (biphenyltetracarboxylic dianhydride) and PMDA (pyromellitic dianhydride) as a polymerization component, and an organic solvent having a partition coefficient Log P of 25 ° C. is positive. A polyimide precursor composition comprising, however, the molar ratio of BPDA and PMDA is 40:60 to 60:40, and 8 to 20% by weight of amine-modified methylphenylsilicone oligomers at both ends based on the total weight of the total polymerization component:
[Formula 1]

According to claim 1,
A polyimide precursor composition in which the both-terminal amine-modified methylphenylsilicone oligomer has a structure of the following Chemical Formula 2:
[Formula 2]

In Formula 2,
R is an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 24 carbon atoms,
p and q are mole fractions, and when p+q=100, p is 70-90 and q is 10-30. According to claim 1,
The polyimide precursor composition comprising the both-terminal amine-modified methylphenyl silicone oligomer in an amount of 10 to 20 wt% based on the total weight of the total polymerization component. According to claim 1,
The solvent in which LogP is positive is N,N-diethylacetamide (N,N-diethylacetamide, DEAc), N,N-diethylformamide (N,N-diethylformamide, DEF), N-ethylpyrrolidone (N -ethylpyrrolidone, NEP), dimethylpropionamide (DMPA) and diethylpropionamide (DEPA) at least one polyimide precursor composition selected from. According to claim 1,
The polyimide precursor composition comprising the amine-modified methylphenyl silicon oligomer at both ends in an amount of 10 to 20 wt% based on the total weight of the total polymerization component, and in which cloudiness (haze) of the polyimide precursor composition does not occur in the above range. According to claim 1,
The polyimide precursor composition comprising the BPDA (biphenyltetracarboxylic dianhydride) and PMDA (pyromellitic dianhydride) in a molar ratio of 50-60:50-40. According to claim 1,
The polyimide precursor composition of the polyimide precursor composition comprising an adhesion promoter in an amount of 0.05 to 3 parts by weight based on 100 parts by weight of the total solid content. 8. The method of claim 7,
A polyimide precursor composition wherein the adhesion promoter has a structure of Formula 5 or Formula 6:
[Formula 5]

[Formula 6]

In Formulas 5 and 6,
Q1 is a tetravalent organic group having 1 to 30 carbon atoms or _a tetravalent organic group represented by R a -LR _{b , wherein R a} and R _b are each independently an aliphatic group having 4 to 10 carbon atoms, an aromatic group having 6 to 24 carbon atoms, It is selected from cyclic aliphatic having 3 to 24 carbon atoms, and L is a single bond, -O-, -CR'R"-, -C(=O)-, -C(=O)O-, -C(= O) NH-, -S-, -SO ₂ -, a phenylene group, and a combination thereof, wherein R' and R" are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, and a carbon number It is selected from the group consisting of 1 to 10 fluoroalkyl groups,
Q ₂ is a divalent organic group having 1 to 30 carbon atoms or a divalent organic group represented by _{R c} -LR _{d , wherein R c} and R _d are each independently an aliphatic group having 4 to 10 carbon atoms or an aromatic group having 6 to 24 carbon atoms. , a cyclic aliphatic having 3 to 24 carbon atoms, and L is a single bond, -O-, -CR'R"-, -C(=O)-, -C(=O)O-, -C( =O)NH-, -S-, -SO ₂ -, a phenylene group and a combination thereof, wherein R' and R" are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, and It is selected from the group consisting of a fluoroalkyl group having 1 to 10 carbon atoms,
R ₁ and R ₃ are each independently an alkyl group having 1 to 5 carbon atoms,
R ₂ and R ₄ are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms,
a and b are each independently an integer of 1 to 3. A polyimide film prepared from the polyimide precursor composition according to any one of claims 1 to 8. 10. The method of claim 9,
A polyimide film having a glass transition temperature of 390° C. or higher of the polyimide film. 10. The method of claim 9,
The polyimide film whose haze of the said polyimide film is 1 or less. 10. The method of claim 9,
A polyimide film having a thickness direction retardation of the polyimide film of 100 nm or less. A flexible device comprising the polyimide film of claim 9 as a substrate. applying the polyimide precursor composition of claim 1 on a carrier substrate;
forming a polyimide film by heating the polyimide precursor composition to imidize the polyamic acid;
forming a device on the polyimide film; and
and peeling the polyimide film on which the element is formed from the carrier substrate. 15. The method of claim 14,
The manufacturing process of the flexible device, wherein the manufacturing process includes a LTPS (low temperature polysilicon) process, an ITO process, or an oxide process.

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