CN112601739B

CN112601739B - Diamine compound, polyimide precursor using same, and polyimide film

Info

Publication number: CN112601739B
Application number: CN201980055368.9A
Authority: CN
Inventors: 丘冀哲; 金炅焕
Original assignee: LG Chem Ltd
Current assignee: LG Chem Ltd
Priority date: 2018-12-12
Filing date: 2019-12-11
Publication date: 2023-09-22
Anticipated expiration: 2039-12-11
Also published as: TW202030180A; KR20200072418A; CN112601739A; KR102569792B1; TWI829825B

Abstract

Disclosed are novel diamines having a structure containing a intramolecular imide group and additionally containing an aromatic ring group substituted with an amide group at the opposite side of the imide group. The use of the novel diamine as a polymeric component in the production of polyimide can provide a polyimide film having significantly improved mechanical and thermal properties while maintaining optical properties.

Description

Diamine compound, polyimide precursor using same, and polyimide film

Technical Field

The present application claims the benefit of priority from korean patent application No. 10-2018-0160168, which was filed on 12 months of 2018, and korean patent application No. 10-2019-0163512, which was filed on 10 months of 2019, 12, the entire disclosures of which are incorporated herein by reference.

The present application relates to a novel diamine, and a polyimide precursor and a polyimide film using the same.

Background

In recent years, weight reduction and miniaturization of products have been emphasized in the field of displays. The glass substrates currently in use are heavy and brittle and difficult to apply to continuous processes. Accordingly, research is actively being conducted to apply a plastic substrate, which has advantages of light weight, flexibility, and applicability to a continuous process, and which can replace a glass substrate, to mobile phones, notebook computers, and PDAs.

In particular, polyimide (PI) resins have advantages of easy synthesis, can be formed into a thin film, and do not require a crosslinking agent for curing. Recently, polyimide is widely used as an integration material in semiconductors such as LCDs, PDPs, and the like due to weight reduction and precision of electronic products. In particular, many studies have been made on the application of PI to a flexible plastic display panel having light and flexible characteristics.

Polyimide (PI) films produced by film-forming polyimide resins are generally prepared by: solution polymerization of aromatic dianhydride with aromatic diamine or aromatic diisocyanate is performed to prepare a solution of polyamic acid derivative, which is coated on a silicon wafer or glass, and cured by heat treatment.

Flexible devices involving high temperature processes require heat resistance at high temperatures. In particular, organic Light Emitting Diode (OLED) devices fabricated using Low Temperature Polysilicon (LTPS) methods may have process temperatures approaching 500 ℃. However, at this temperature, thermal decomposition by hydrolysis tends to occur even with polyimide having excellent heat resistance. Therefore, in order to manufacture a flexible device, excellent chemical resistance and storage stability must be ensured so that thermal decomposition caused by hydrolysis does not occur during a high temperature process.

In addition, aromatic polyimide resins exhibit poor processability and brown coloration due to intramolecular interactions and charge transfer complexes (charge transfer complexation, CTC). To overcome this, attempts have been made to introduce aliphatic chains, flexible linking groups, fluorinated functional groups, etc. into monomers used in the production of polyimides. However, the introduction of these substituents causes a problem of deterioration in mechanical properties, i.e., strength, of polyimide.

Therefore, there is a need to develop a technique capable of improving mechanical properties while maintaining the properties of polyimide.

Disclosure of Invention

Technical problem

One problem to be solved by the present invention is to provide new diamines capable of producing polyimides with improved physical properties.

Another problem to be solved by the present invention is to provide a polyimide precursor for producing a polyimide film having improved physical properties.

Yet another problem to be solved by the present invention is to provide a polyimide film prepared by using the polyimide precursor.

The invention also provides a flexible device comprising the polyimide film and a method of manufacturing the flexible device.

Technical proposal

In order to solve the problems of the present invention, a diamine represented by formula 1 is provided.

[ 1]

In the formula (1) of the present invention,

Z ₁ to Z ₈ Each independently is a carbon atom or a nitrogen atom, provided that Z ₁ To Z ₈ Not simultaneously being nitrogen atoms, R ₁ 、R ₂ 、R ₃ And R is ₄ Each independently selected from the group consisting of alkyl groups having 1 to 10 carbon atoms, haloalkyl groups having 1 to 10 carbon atoms, alkenyl groups having 1 to 10 carbon atoms, and aryl groups having 6 to 18 carbon atoms, n1, n2, n3, and n4 are each independently integers of 0 to 4, and X is a single bond or a functional group selected from the group consisting of: -O-, -S-, -C (=o) O-, -CH (OH) -, -S (=o) ₂ -、-Si(CH ₃ ) ₂ -CR 'R "-, -C (=o) NH-, and combinations thereof, wherein R' and R" are each independently selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, and a fluoroalkyl group having 1 to 10 carbon atoms.

According to one embodiment, in formula 1, Z ₁ To Z ₄ At least one of which must be a carbon atom, and Z ₅ To Z ₈ At least one of which must be a carbon atom.

According to one embodiment, in formula 1, R ₁ And R is ₂ May each independently be an alkyl group having 1 to 5 carbon atoms or a haloalkyl group having 1 to 5 carbon atoms, or n1 and n2 may each independently be 0.

According to one embodiment, in formula 1, Z ₁ To Z ₄ All carbon atoms are possible.

According to one embodiment, in formula 1, Z ₁ To Z ₄ At least one of them may be a nitrogen atom or Z ₅ To Z ₈ At least one of them may be a nitrogen atom.

According to one embodiment, in formula 1, Z ₁ To Z ₄ At least one of them may be a nitrogen atom and Z ₅ To Z ₈ At least one of them may be a nitrogen atom.

According to one embodiment, the diamine of formula 1 may be selected from compounds of formulas 1-1 to 1-20.

Furthermore, the present invention provides a polyimide precursor obtained by polymerizing a polymerization component comprising at least one diamine and at least one acid dianhydride,

wherein the diamine in the polymeric component comprises a diamine represented by formula 1.

Furthermore, the present invention provides a polyimide film manufactured by using the polyimide precursor.

According to one embodiment, a polyimide film may be manufactured by a method comprising: applying a polyimide precursor composition comprising a polyimide precursor to a carrier substrate; and

the polyimide precursor composition is heated and cured.

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

Furthermore, the present invention provides a method for manufacturing a flexible display, the method comprising:

Applying a polyimide precursor composition comprising a polyimide precursor to a carrier substrate;

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

forming a device on the polyimide film; and

the polyimide film with the device formed thereon is peeled from the carrier substrate.

According to one embodiment, the method may include an LTPS (low temperature polysilicon) method, an ITO method, or an oxide method.

The present invention provides a process for preparing a diamine having the structure of formula 1, the process comprising the steps of:

reacting a compound of formula (i) with a compound of formula (ii) below to obtain a compound of formula (iii);

reacting a compound of formula (iii) with a compound of formula (iv) to obtain a compound of formula (v); and

reducing a compound of formula (v):

wherein, the liquid crystal display device comprises a liquid crystal display device,

Z _a to Z _d Each independently is a carbon atom or a nitrogen atom, provided that Z _a To Z _d Not simultaneously being nitrogen atoms, R ₁ 、R ₂ And R is _a Each independently selected from alkyl groups having 1 to 10 carbon atoms, haloalkyl groups having 1 to 10 carbon atoms, and alkyl groups having 1 to 10 carbon atomsAlkenyl of 10 carbon atoms, and aryl of 6 to 18 carbon atoms, n ₁ 、n ₂ And n is each independently an integer from 0 to 4, and X is a single bond or a functional group selected from the group consisting of: -O-, -S-, -C (=o) O-, -CH (OH) -, -S (=o) ₂ -、-Si(CH ₃ ) ₂ -CR 'R "-, -C (=o) NH-, and combinations thereof, wherein R' and R" are each independently selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, and a fluoroalkyl group having 1 to 10 carbon atoms.

Advantageous effects

Disclosed is a novel diamine having a structure comprising a intramolecular imide group and further comprising an aromatic ring group substituted with an amide group on both sides of the imide group, which can provide a polyimide film in which mechanical properties and thermal properties are significantly improved while maintaining optical properties when the novel diamine is used as a polymerization component in the production of polyimide.

Detailed Description

Since various modifications and changes may be made in the present invention, specific embodiments are shown in the drawings and will be described in detail in the detailed description. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but to include all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. In the following description of the present invention, if it is determined that detailed description of known functions may obscure the gist of the present invention, detailed description of known functions will be omitted.

In this specification, unless otherwise indicated, all compounds or organic groups may be substituted or unsubstituted. In this context, the term "substituted" means that at least one hydrogen comprised in a compound or an organic group is substituted with a substituent selected from the group consisting of: a halogen atom, an alkyl or haloalkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 10 carbon atoms, a carboxyl group, an aldehyde group, an epoxy group, a cyano group, a nitro group, an amino group, a sulfonic group, or a derivative thereof.

Aromatic polyimides are widely used in high-tech industries, such as microelectronics, aerospace, insulation and fire-resistant materials, due to their excellent overall properties, such as thermal oxidative stability, high mechanical strength and excellent mechanical strength. However, aromatic polyimides having strong absorption in the ultraviolet-visible region exhibit intense coloration ranging from pale yellow to dark brown. This limits its wide application in the photovoltaic field where transparency and colorless properties are essential requirements. The reason for coloration in aromatic polyimide resins is the formation of intramolecular charge transfer complexes (CT-complexes) between alternating electron donors (dianhydrides) and electron acceptors (diamines) in the polymer backbone.

In order to solve the problem, for the development of an optically transparent PI film having a high glass transition temperature (Tg), a method of introducing functional groups, a method of introducing bulky side groups, fluorinated functional groups, etc. into a polymer main chain, or a method of introducing flexible units (-S-, -O-, -CH) have been studied ₂ -etc.). However, the introduction of these substituents may cause a problem of deterioration in mechanical properties, i.e., strength, of the polyimide.

Accordingly, the present invention provides a diamine represented by the following formula 1 as a polymerization component capable of producing polyimide having improved mechanical properties.

[ 1]

In the formula (1) of the present invention,

Z ₁ to Z ₈ Each independently is a carbon atom or a nitrogen atom, provided that Z ₁ To Z ₈ Not both the nitrogen atom and the hydroxyl group,

R ₁ 、R ₂ 、R ₃ and R is ₄ Each independently selected from the group consisting of alkyl groups having 1 to 10 carbon atoms, haloalkyl groups having 1 to 10 carbon atoms, alkenyl groups having 1 to 10 carbon atoms, and aryl groups having 6 to 18 carbon atoms,

n1, n2, n3 and n4 are each independently integers from 0 to 4, and

x is a single bond or a functional group selected from the group consisting of: -O-, -S-, -C (=o) O-, -CH (OH) -, -S (=o) ₂ -、-Si(CH ₃ ) ₂ -CR 'R "-, -C (=o) NH-, and combinations thereof, wherein R' and R" are each independently selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, and a fluoroalkyl group having 1 to 10 carbon atoms.

Since the diamine according to the present invention contains a diamine containing an imide group in a molecule, a Charge Transfer Coordination (CTC) effect is improved by an increase in intermolecular pi-pi electron interactions of diamine repeating units containing an imide group during polymerization of polyimide. Thus, the mechanical properties are improved and the distance between molecules is closer, so that the probability of polymerization is increased and thus the molecular weight can be increased. Further, since the aromatic structure is continuously linked due to the structure comprising the aromatic ring group substituted with the amide group linked to both sides of the imide group, the improved CTC effect is suppressed and the workability is improved. That is, while improving mechanical characteristics due to the increased CTC effect caused by the increased imidization rate, the CTC effect can be suppressed by the amide group.

According to another embodiment, Z ₁ To Z ₄ At least one of them may be a nitrogen atom or Z ₅ To Z ₈ At least one of which may be a nitrogen atom, according to another embodiment Z ₁ To Z ₄ At least one of them may be a nitrogen atom and Z ₅ To Z ₈ At least one of them may be a nitrogen atom.

According to one embodiment, the diamine of formula 1 may be prepared by the same reaction as in scheme 1 below:

scheme 1

Wherein Z is _a To Z _d Each independently is a carbon atom or a nitrogen atom, provided that Z _a To Z _d Not both the nitrogen atom and the hydroxyl group,

R ₁ 、R ₂ and R is _a Each independently selected from the group consisting of alkyl groups having 1 to 10 carbon atoms, haloalkyl groups having 1 to 10 carbon atoms, alkenyl groups having 1 to 10 carbon atoms, and aryl groups having 6 to 18 carbon atoms, n ₁ 、n ₂ And n is each independently an integer from 0 to 4, and

x is the same as defined in formula 1.

In step (1) of scheme 1, the compound of formula (i) is reacted with the compound of formula (ii) to obtain the compound of formula (iii).

The compound of formula (i) and the compound of formula (ii) may be used in a molar ratio of from 1:0.3 to 1:1, for example in a molar ratio of from 1:0.3 to 1:0.7.

In the reaction of step (1), tetrahydrofuran (THF), ethyl Acetate (EA), or the like may be used as an organic solvent, and propylene oxide may be added as a catalyst to improve the reactivity.

Furthermore, in order to reduce the strong reaction due to the high reactivity, the reaction is advantageously carried out at-30 ℃ to 0 ℃, for example at-20 ℃, and the reaction time may be 1 to 5 hours, for example 1 to 3 hours.

In step (2) of scheme 1, the compound of formula (iii) is reacted with the compound of formula (iv) to obtain the compound of formula (v).

The compound of formula (iii) and the compound of formula (iv) may be used in a molar ratio of from 1:0.3 to 1:1, for example in a molar ratio of from 1:0.3 to 1:0.7.

In the reaction of step (2), acetic acid, propionic acid, etc. may be used to disperse the reaction compound, and the reaction temperature may be raised to about 100 ℃, and the reaction time may be 3 hours to 5 hours, for example, 4 hours.

Subsequently, after the reaction temperature is lowered to room temperature, alcohols such as ethanol and isopropanol may be added to obtain a solid.

In step (3) of scheme 1, the compound of formula (v) is reduced to finally obtain the compound of formula 1.

The reduction reaction in step (3) may be carried out in the presence of a palladium on carbon (Pd/C) catalyst in a hydrogen atmosphere for 12 hours to 18 hours, for example, for 16 hours. In this case, N-methylpyrrolidone, tetrahydrofuran, etc. can be used as a dispersion medium.

According to one embodiment, the weight average molecular weight of the polyimide precursor prepared by using the diamine having the above structure may exceed 50,000g/mol to improve mechanical properties. For example, the polyimide precursor may have a weight average molecular weight of 51,000g/mol to 65,000g/mol. When the molecular weight is 50,000g/mol or less, the viscosity of the solution is lowered due to the decrease in reactivity of polyimide, and the viscosity is low compared with the solid content, so that the film thickness may not be easily controlled during the solution coating process and the final curing process. Further, when the molecular weight is low, mechanical properties may be lowered, which may cause a problem of lowering the film strength.

According to one embodiment, by including a nitrogen atom in an aromatic ring substituted with an amide group, CTC effect may be reduced to improve optical characteristics.

In formula 1, a substituent (e.g., a substituent such as a fluoroalkyl group) containing a fluorine atom (F) may reduce stacking within the structure or between chains of polyimide, and may weaken electrical interaction between chromophores due to steric and electrical effects, thereby producing high transparency in the visible light region.

The polyimide precursor according to the present invention may further comprise a diamine having the structure of formula 2 as a polymerization component:

[ 2]

In the formula (2) of the present invention,

R ₅ and R is ₆ Each independently is a monovalent organic group having 1 to 20 carbon atoms, and h is an integer of 3 to 200.

More specifically, the compound of formula 2 may be a diamine compound of the following formula 2-1.

[ 2-1]

In the formula 2-1 of the present invention,

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

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

The compound of formula 2 may be present at 5 to 50 wt% relative to the total weight of the polymeric component, preferably at 10 to 20 wt% relative to the total weight of the polymeric component.

When the polymeric component including the structure of formula 2 is excessively added with respect to the total weight of the polymeric component, mechanical properties of polyimide such as modulus may be deteriorated and film strength may be lowered, resulting in physical damage such as tearing of the film during the process. Further, when the diamine having the structure of formula 2 is excessively added, tg derived from the polymer having a siloxane structure may occur, and thus Tg occurs at a low process temperature of 350 ℃ or less, and during an inorganic film deposition process of 350 ℃ or more, wrinkles may occur on the film surface due to a flow phenomenon of the polymer, thereby generating cracks of the inorganic film.

In general, in the case where polyimide contains 10 wt% or more of diamine containing the silicone oligomer structure of formula 2 in the polymerization component, the effect of reducing residual stress can be improved, and in the case of more than 50 wt%, tg is less than 390 ℃, so that heat resistance may be lowered.

On the other hand, although the silicone oligomer is contained in an amount of 10% by weight or more based on the total polymerization component, the polyimide according to the present invention can maintain a Tg of 390 ℃ or more. Therefore, the effect of reducing the residual stress caused by the silicone oligomer structure can be achieved while maintaining the glass transition temperature at 390 ℃ or higher.

The molecular weight of the silicone oligomer structure contained in the diamine having the structure of formula 2 may be 4000g/mol or more, wherein the molecular weight means a weight average molecular weight, and the molecular weight may be calculated by calculating the equivalent of a reactive group such as amine or dianhydride using NMR analysis or acid-base titration.

When the molecular weight of the silicone oligomer structure including the structure of formula 2 is less than 4000g/mol, heat resistance may be reduced, for example, glass transition temperature (Tg) of the prepared polyimide may be reduced, or thermal expansion coefficient may be excessively increased.

According to the present invention, the silicone oligomer domains distributed in the polyimide matrix have a continuous phase, for example, a size of nano-size, for example, 1nm to 50nm, or 5nm to 40nm, or 10nm to 30nm, so that residual stress can be minimized while maintaining heat resistance and mechanical properties. If it does not have such a continuous phase, there may be a residual stress reducing effect, but it is difficult to use in the method due to significant reduction in heat resistance and mechanical properties.

Here, the domain of the silicone oligomer means a region in which a polymer having a silicone oligomer structure is distributed, and the size thereof means a diameter of a circle surrounding the region.

It is preferred that the portions (domains) comprising the silicone oligomer structure are connected in a continuous phase in the polyimide matrix, wherein the continuous phase means a shape in which the nano-sized domains are uniformly distributed.

Thus, according to the present invention, the silicone oligomer can be uniformly distributed in the polyimide matrix without phase separation despite having a high molecular weight, so that the haze characteristics are reduced to obtain polyimide having higher transparency characteristics. Furthermore, the presence of the silicone oligomer structure in the continuous phase can more effectively improve the mechanical strength and stress relaxation effect of the polyimide. Because of these properties, the composition according to the present invention can provide a flat polyimide film with improved thermal and optical properties by reducing the bending of the substrate after the coating is cured.

In the present invention, by inserting the silicone oligomer structure into the polyimide structure, the modulus of the polyimide can be suitably improved, and also the stress caused by external force can be relaxed. Polyimides comprising a silicone oligomer structure may exhibit polarity and phase separation may occur due to a polarity difference from polyimide structures not comprising a siloxane structure, whereby the siloxane structure may be unevenly distributed throughout the polyimide structure. In this case, it is difficult to exhibit an improvement effect of physical properties of polyimide such as strength improvement and stress relaxation due to a siloxane structure, and haze is increased due to phase separation, thereby deteriorating transparency of the film. In particular, when the diamine including a siloxane structure has a high molecular weight, the polarity of the polyimide thus prepared may be more pronounced, so that the phase separation phenomenon between the polyimides may be more pronounced. At this time, when a siloxane diamine having a low molecular weight structure is used, a large amount of siloxane diamine must be added to exhibit effects such as stress relaxation. However, this may cause process problems such as low Tg, and thus may deteriorate physical properties of the polyimide film. Therefore, in the case of adding a siloxane diamine having a high molecular weight, a large relaxing segment can be formed in the molecule, and thus a stress relaxing effect can be effectively exhibited even with a small amount of addition, compared with the case of adding a siloxane diamine having a low molecular weight. Accordingly, the present invention can be more uniformly distributed in the polyimide matrix without phase separation by using the compound of formula 2 having a siloxane structure with a high molecular weight.

According to one embodiment, as the acid dianhydride used for polymerizing the polyimide precursor, tetracarboxylic acid dianhydride may be used. For example, as the tetracarboxylic dianhydride, a tetracarboxylic dianhydride containing an aliphatic, alicyclic, or aromatic tetravalent organic group in the molecule, or a combination thereof, wherein the aliphatic, alicyclic, or aromatic tetravalent organic groups are linked to each other via a crosslinked structure, may be used. Preferably, it may include an acid dianhydride having a structure having a single ring or multiple ring aromatic, single ring or multiple ring alicyclic groups, or two or more of them are connected through a single bond or a functional group. Alternatively, it may comprise a tetracarboxylic dianhydride comprising a tetravalent organic group having an aliphatic or aromatic ring, wherein each ring is a monocyclic structure, each ring is fused to form a heterocyclic structure, or each ring is linked by a single bond.

For example, the tetracarboxylic dianhydride may include a tetracarboxylic dianhydride containing a tetravalent organic group selected from the structures of the following formulas 3a to 3 e.

[ 3a ]

[ 3b ]

[ 3c ]

[ 3d ]

[ 3e ]

In the formulae 3a to 3e, R ₁₁ To R ₁₇ Each independently is a member selected from the group consisting ofAnd (3) substitution: halogen atoms selected from the group consisting of-F, -Cl, -Br and-I, hydroxy (-OH), thiol (-SH), nitro (-NO) ₂ ) Cyano, alkyl having 1 to 10 carbon atoms, haloalkoxy having 1 to 4 carbon atoms, haloalkyl having 1 to 10 carbon atoms, and aryl having 6 to 20 carbon atoms,

a1 is an integer of 0 to 2, a2 is an integer of 0 to 4, a3 is an integer of 0 to 8, a4 and a5 are each independently an integer of 0 to 3, a6 and a9 are each independently an integer of 0 to 3, and a7 and a8 are each independently an integer of 0 to 7,

A ₁₁ and A ₁₂ Each independently selected from a single bond, -O-, -CR 'R "(wherein R' and R" are each independently selected from a hydrogen atom, an alkyl group having 1 to 10 carbon atoms (e.g., methyl, ethyl, propyl, isopropyl, n-butyl, t-butyl, pentyl, etc.), and a haloalkyl group having 1 to 10 carbon atoms (e.g., trifluoromethyl, etc.), -C (=o) -, -C (=o) O-, -C (=o) NH-, -S-, -SO ₂ -、-O[CH ₂ CH ₂ O]y- (y is an integer from 1 to 44), -NH (c=o) NH-, -NH (c=o) O-, a mono-or polycyclic cycloalkylene group having 6 to 18 carbon atoms (e.g., cyclohexylene, etc.), a mono-or polycyclic arylene group having 6 to 18 carbon atoms (e.g., phenylene, naphthylene, fluorenylene, etc.), and combinations thereof.

Alternatively, the tetracarboxylic dianhydride may contain a tetravalent organic group selected from the following formulas 4a to 4 n.

At least one hydrogen atom in the tetravalent organic group of formulas 4a to 4n may be substituted with a substituent selected from the group consisting of: halogen atoms selected from the group consisting of-F, -Cl, -Br and-I, hydroxy (-OH), thiol (-SH), nitro (-NO) ₂ ) Cyano, alkyl having 1 to 10 carbon atoms, haloalkoxy having 1 to 4 carbon atoms, haloalkyl having 1 to 10 carbon atoms and aryl having 6 to 20 carbon atoms. For example, the halogen atom may be fluorine (-F), and the haloalkyl group is a fluoroalkyl group having 1 to 10 carbon atoms containing a fluorine atom, optionallyFrom fluoromethyl, perfluoroethyl, trifluoromethyl, and the like. The alkyl group may be selected from methyl, ethyl, propyl, isopropyl, t-butyl, pentyl and hexyl, and the aryl group is selected from phenyl and naphthyl. More preferably, at least one hydrogen atom in the tetravalent organic group of formulas 4a to 4n may be substituted with a fluorine atom or a substituent containing a fluorine atom such as fluoroalkyl.

Alternatively, the tetracarboxylic dianhydride may contain a tetravalent organic group containing an aliphatic or aromatic ring, in which each ring is a rigid structure (i.e., a monocyclic structure), each ring is linked by a single bond, or each ring is directly linked to form a heterocyclic structure.

According to one embodiment, as the polymerization component of the polyimide, one or more diamines may be contained in addition to the diamine of formula 1 and optionally the diamine of formula 2. For example, it may comprise a diamine comprising a divalent organic group selected from the group consisting of: a monocyclic or polycyclic aromatic divalent organic group having 6 to 24 carbon atoms, a monocyclic or polycyclic alicyclic divalent organic group having 6 to 18 carbon atoms, or a divalent organic group having a structure in which two or more of them are connected through a single bond or a functional group. Alternatively, it may comprise a diamine containing a divalent organic group having an aliphatic or aromatic ring, wherein each ring is a monocyclic structure, each ring is fused to form a heterocyclic structure, or each ring is linked by a single bond.

For example, the diamine may comprise a divalent organic group selected from the following formulas 5a to 5 e.

[ 5a ]

[ 5b ]

[ 5c ]

[ 5d ]

[ 5e ]

In the formulae 5a to 5e,

R ₂₁ to R ₂₇ Each independently is a substituent selected from the group consisting of: halogen atoms selected from the group consisting of-F, -Cl, -Br and-I, hydroxy (-OH), thiol (-SH), nitro (-NO) ₂ ) Cyano, alkyl having 1 to 10 carbon atoms, haloalkoxy having 1 to 4 carbon atoms, haloalkyl having 1 to 10 carbon atoms and aryl having 6 to 20 carbon atoms,

A ₂₁ and A ₂₂ Each independently selected from a single bond, -O-, -CR 'R "(wherein R' and R" are each independently selected from a hydrogen atom, an alkyl group having 1 to 10 carbon atoms (e.g., methyl, ethyl, propyl, isopropyl, n-butyl, t-butyl, pentyl, etc.), and a haloalkyl group having 1 to 10 carbon atoms (e.g., trifluoromethyl, etc.), -C (=o) -, -C (=o) O-, -C (=o) NH-, -S-, -SO ₂ -、-O[CH ₂ CH ₂ O]y- (y is an integer of 1 to 44), -NH (C=O) NH-, -NH (C=O) O-, a monocyclic or polycyclic cycloalkylene group having 6 to 18 carbon atoms (e.g., cyclohexylene, etc.), a monocyclic or polycyclic arylene group having 6 to 18 carbon atoms (e.g., phenylene, naphthylene, fluorenylene, etc.), and combinations thereof,

b1 is an integer from 0 to 4, b2 is an integer from 0 to 6, b3 is an integer from 0 to 3, b4 and b5 are each independently an integer from 0 to 4, b7 and b8 are each independently an integer from 0 to 9, and b6 and b9 are each independently an integer from 0 to 3.

For example, the diamine may comprise a divalent organic group selected from the following formulas 6a to 6 p.

Alternatively, the diamine may comprise a divalent organic group in which an aromatic ring or aliphatic structure forms a rigid chain structure, for example, a divalent organic group having an aliphatic ring or aromatic ring, in which each ring is a monocyclic structure, each ring is linked by a single bond, or each ring is fused to form a heterocyclic structure.

According to one embodiment of the invention, the reaction molar ratio of the acid dianhydride to the diamine may be from 1:1.1 to 1.1:1. The reaction molar ratio may vary depending on the desired reactivity and processability. According to one embodiment of the invention, the molar ratio of acid dianhydride to diamine may be from 1:0.98 to 0.98:1, preferably from 1:0.99 to 0.99:1.

The reaction of the acid dianhydride with the diamine may be carried out by a conventional polymerization method such as solution polymerization of the polyimide or its precursor.

Organic solvents that may be used in the polymerization of the polyamic acid may include: ketones such as gamma-butyrolactone, 1, 3-dimethyl-2-imidazolidinone, methyl ethyl ketone, cyclohexanone, cyclopentanone, and 4-hydroxy-4-methyl-2-pentanone; aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; glycol ethers (cellosolves) such as ethylene glycol monoethyl ether, ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, dipropylene glycol diethyl ether and triethylene glycol monoethyl ether; ethyl acetate, butyl acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, dipropylene glycol monomethyl ether acetate, ethanol, propanol, ethylene glycol, propylene glycol, carbitol, dimethyl propionamide (DMPA), diethyl propionamide (DEPA), dimethyl acetamide (DMAc), N-diethyl acetamide, dimethyl formamide (DMF), diethyl formamide (DEF), N-methylpyrrolidone (NMP), N-ethylpyrrolidone (NEP), N-dimethylmethoxyacetamide, dimethyl sulfoxide, pyridine, dimethyl sulfone, hexamethylphosphoramide, tetramethyl urea, N-methylcaprolactam, tetrahydrofuran, m-dimethyl pyrrolidone (NMP) Alkane, p-di->Alkane, 1, 2-dimethoxyethane, bis (2-methoxyethyl) ether, 1, 2-bis (2-methoxyethoxy) ethane, bis [2- (2-methoxyethoxy)]Ethers, equamide M100, equamide B100, etc., and these solvents may be used alone or as a mixture of two or more.

According to one embodiment, as the organic solvent for polymerizing the polymerization component, a solvent having a positive partition coefficient (Log P) at 25 ℃ may be used. By using an organic solvent having a positive Log P, tg can be maintained at a high temperature of 390 ℃ or higher even for a composition in which a methylphenyl silicone oligomer is contained in an amount of 10 wt% or more.

The organic solvent having a positive partition coefficient as described above can reduce white turbidity caused by phase separation due to a polarity difference between the flexible polyimide repeating structure and other polyimide structure containing a siloxane structure such as a silicone oligomer. Conventionally, in order to solve the phase separation problem, two organic solvents are used. However, the present invention can reduce white turbidity due to phase separation even with one organic solvent, so that a more transparent polyimide film can be produced.

There is a method of mixing a polar solvent and a nonpolar solvent to solve the above problems. However, since the polar solvent has high volatility, it may volatilize in advance during the production process, which may cause problems such as deterioration of process reproducibility. In addition, the problem of phase separation may not be completely solved, resulting in high haze and low transparency of the produced polyimide film.

More specifically, by using a solvent whose molecule has a hydrophilic-lipophilic structure, the process problem caused by using a polar solvent can be solved. Furthermore, due to the hydrophilic-lipophilic molecule structure, the polyimide can be uniformly distributed even if only one solvent is used, which makes it very suitable for solving the problems caused by phase separation. Accordingly, a polyimide in which haze characteristics are significantly improved can be provided.

The positive partition coefficient value of the solvent means that the polarity of the solvent is hydrophobic. According to the studies of the present inventors, it was found that the edge-back phenomenon is improved when a specific solvent having a positive partition coefficient value is used to prepare a polyimide precursor composition. Further, in the present invention, by using a solvent having positive Log P as described above, the edge back phenomenon of the solution can be controlled without using an additive such as a leveling agent for controlling the surface tension of the material and the smoothness of the coating film. Since no additional additives such as additives are used, quality problems and process problems such as the presence of low molecular substances in the final product can be eliminated, and polyimide films having uniform properties can be formed more effectively.

For example, in the process of coating a polyimide precursor composition on a glass substrate, edge-back phenomenon may occur due to shrinkage of the coating layer during curing or under the condition of allowing the coating solution to stand in a humid condition. The edge-back phenomenon of the coating solution may cause a change in film thickness. Therefore, since the film lacks flex resistance, the film may be cut off at the time of cutting or the edge of the film may be damaged, thereby causing problems of poor process operability and reduced yield.

Further, when a fine foreign matter having polarity is introduced into a polyimide precursor composition applied on a substrate, for a polyimide precursor composition including a polar solvent having negative Log P, coating cracks or thickness variation based on the position of the foreign matter may occur sporadically due to the polarity of the foreign matter. In the case of using a hydrophobic solvent having positive Log P, even when a fine foreign matter having polarity is introduced, occurrence of thickness variation due to cracks of the coating layer can be reduced or suppressed.

Specifically, in the polyimide precursor composition including the solvent having positive Log P, an edge back ratio (edge back ratio) defined by the following equation 1 may be 0% to 0.1% or less.

[ equation 1]

Edge-back ratio (%) = [ (a-B)/a ] ×100

a: the area of the polyimide precursor composition completely coated on the substrate (100 mm. Times.100 mm),

b: area after edge-receding phenomenon occurs from the edge of the substrate on which the polyimide precursor composition or PI film is coated.

Edge receding phenomena of the polyimide precursor composition and the film may occur within 30 minutes after the polyimide precursor composition solution is applied, and in particular, the film may be rolled up from the edge to make the thickness of the edge thicker.

After the polyimide precursor composition according to the present invention is coated on a substrate and then left to stand in a humidity condition for 10 minutes or more (e.g., 10 minutes or more, e.g., 40 minutes or more), the edge receding ratio of the coated resin composition solution may be 0.1% or less. For example, even after standing at a temperature of 20 ℃ to 30 ℃ and in a humidity condition of 40% or more (more specifically, in a humidity condition in the range of 40% to 80%, i.e., in each humidity condition of 40%, 50%, 60%, 70%, 80%, for example, in a humidity condition of 50%), the edge receding ratio may be 0.1% or less, preferably 0.05%, more preferably almost 0%.

After the polyimide precursor composition is coated on a substrate and then left to stand for 10 minutes to 50 minutes at a temperature of 20 ℃ to 30 ℃ and in a humidity condition of 40% or more (more specifically, in a humidity condition in the range of 40% to 80%, i.e., in each humidity condition of 40%, 50%, 60%, 70%, 80%, for example, in a humidity condition of 50%), the edge back ratio as described above is maintained even after curing, for example, the edge back ratio of the coated resin composition solution is 0.1% or less. That is, even during the curing by the heat treatment, there may be little or no edge back phenomenon, and specifically, the edge back ratio may be 0.05% or less, more preferably, almost 0%.

By solving such edge receding phenomenon, the polyimide precursor composition according to the present invention can obtain a polyimide film having higher uniform characteristics, thereby further improving the productivity of the manufacturing process.

In addition, the density of the solvent according to the invention, as measured by standard ASTM D1475, may be 1g/cm ³ Or smaller. If the density is greater than 1g/cm ³ The relative viscosity may increase and the process efficiency may decrease.

The solvent having a positive partition coefficient (Log P) may be at least one selected from the group consisting of N, N-diethylacetamide (DEAc), N-Diethylformamide (DEF), N-ethylpyrrolidone (NEP), dimethylpropionamide (DMPA) and Diethylpropionamide (DEPA).

The boiling point of the solvent may be 300 ℃ or less. More specifically, the partition coefficient Log P at 25 ℃ may be 0.01 to 3, or 0.01 to 2, or 0.1 to 2.

The partition coefficient may be calculated using the ACD/Log P module of the ACD/Percepa platform from ACD/Labs. The ACD/Log P module uses an algorithm based on the QSPR (Quantitative Structure-Property Relationship ) method using a 2D molecular structure.

In addition, aromatic hydrocarbons such as xylene and toluene may also be used. To facilitate dissolution of the polymer, about 50% by weight or less of an alkali metal salt or alkaline earth metal salt may also be added to the solvent, based on the total amount of solvent.

In addition, in the case of synthesizing polyamic acid or polyimide, a capping agent in which the terminal of the molecule is reacted with dicarboxylic anhydride or monoamine to terminate the terminal of polyimide may be further added to inactivate excessive polyamino groups or anhydride groups.

The reaction of the tetracarboxylic dianhydride with the diamine may be carried out by a conventional polymerization method of polyimide precursors, such as solution polymerization. Specifically, it can be prepared by: diamine is dissolved in an organic solvent, and then tetracarboxylic dianhydride is added to the resulting mixed solution to perform polymerization.

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

The reaction temperature during the polymerization reaction may be-20 to 80 ℃, preferably 0 to 80 ℃. If the reaction temperature is too high, the reactivity may become high, the molecular weight may become large, and the viscosity of the precursor composition may increase, which may be disadvantageous in terms of process.

In view of workability such as coating characteristics during film formation, the polyamic acid solution prepared according to the above-described manufacturing method preferably contains solid content in an amount such that the composition has an appropriate viscosity.

The polyimide precursor composition comprising the polyamic acid may be in the form of a solution dissolved in an organic solvent. For example, when the polyimide precursor is synthesized in an organic solvent, the solution may be a reaction solution as obtained, or may be obtained by diluting the reaction solution with another solvent. When the polyimide precursor is obtained as a solid powder, it may be dissolved in an organic solvent to prepare a solution.

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

The polyimide precursor composition may be adjusted to have a viscosity of 3,000cp or more at a solid content concentration of 20 wt% or less, and the polyimide precursor composition may be adjusted to have a viscosity of 10,000cp or less, preferably 9,000cp or less, more preferably 8,000cp or less. When the viscosity of the polyimide precursor composition is more than 10,000cp, the efficiency of defoaming during processing of the polyimide film is reduced. This not only results in a decrease in the efficiency of the process, but also results in degradation of the surface roughness of the produced film due to bubble generation. This may lead to deterioration of electrical, optical and mechanical properties.

Then, the polyimide precursor produced by the polymerization reaction may be imidized by chemical imidization or thermal imidization to prepare a transparent polyimide film.

According to one embodiment, a polyimide film may be manufactured by a method comprising: applying a polyimide precursor composition to a substrate; and

the applied polyimide precursor composition is heated and cured.

As the substrate, a glass substrate, a metal substrate, a plastic substrate, or the like can be used without any particular limitation. Among them, such a glass substrate may be preferable: which is excellent in thermal stability and chemical stability during imidization and curing processes for polyimide precursors, and can be easily separated even without any treatment with an additional release agent, while not damaging a polyimide film formed after curing.

The application process may be performed according to conventional application methods. Specifically, spin coating, bar coating, roll coating, air knife, gravure, reverse roll, contact roll, doctor blade, spray coating, dipping, brush coating, and the like can be used. Among them, it is more preferable to conduct by a casting method which allows a continuous process and enables the imidization rate of polyimide to be improved.

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

Specifically, it may be applied in an amount such that the thickness is 10 μm to 30 μm. After the polyimide precursor composition is applied, a drying process may also optionally be performed to remove the solvent remaining in the polyimide precursor composition before the curing process.

The drying process may be performed according to a conventional method. Specifically, the drying process may be performed at a temperature of 140 ℃ or less, or 80 ℃ to 140 ℃. If the drying temperature is lower than 80 ℃, the drying process becomes longer. If the drying temperature exceeds 140 ℃, imidization proceeds rapidly, making it difficult to form a polyimide film having a uniform thickness.

The polyimide precursor composition is then applied to a substrate and heat treated in an IR oven, in a hot air oven, or on a hot plate. The heat treatment temperature may be 300 ℃ to 500 ℃, preferably 320 ℃ to 480 ℃. The heat treatment may be performed in a multi-step heating process within the above temperature range. The heat treatment process may be performed for 20 minutes to 70 minutes, and preferably for 20 minutes to 60 minutes.

The residual stress immediately after curing of the polyimide film prepared as described above may be 40MPa or less, and the residual stress change after leaving the polyimide film at 25 ℃ and 50% humidity for 3 hours may be 5MPa or less.

The yellowness of the polyimide film may be 15 or less, and is preferably 13 or less. Further, the haze of the polyimide film may be 2 or less, and is preferably 1 or less.

Further, the polyimide film may have a transmittance at 450nm of 75% or more, a transmittance at 550nm of 85% or more, and a transmittance at 630nm of 90% or more.

The polyimide film may have high heat resistance, for example, a thermal decomposition temperature (td_1%) in which a mass loss is 1% may be 500 ℃ or higher.

The polyimide film prepared as described above may have a modulus of 3GPa to 6GPa. When the modulus (elastic modulus) is less than 3GPa, the film has low rigidity and is easily fragile against external impact. When the elastic modulus exceeds 6GPa, the rigidity of the cover film (cover film) is excellent, but sufficient flexibility may not be obtained.

Further, the polyimide film may have an elongation of 90% or more, preferably 92% or more, and a tensile strength of 130MPa or more, preferably 140MPa or more.

In addition, the polyimide film according to the present invention may have excellent thermal stability against temperature variation. For example, after n+1 heating and cooling processes in the temperature range of 100 ℃ to 350 ℃, the coefficient of thermal expansion may be-10 ppm/°c to 100ppm/°c, preferably-7 ppm/°c to 90ppm/°c, more preferably 80ppm/°c or less (n is an integer of at least 0).

Further, the retardation (R _th ) May be-150 nm to +150nm, preferably-130 nm to +130nm, thereby exhibiting optical isotropy to improve visual acuityDegree.

According to one embodiment, the adhesion force of the polyimide film to the carrier substrate may be 5gf/in or more, and preferably 10gf/in or more.

Furthermore, the present invention provides a method for manufacturing a flexible device, the method comprising the steps of:

preparing a polyimide precursor composition;

applying a polyimide precursor composition on a carrier substrate, and then heating to imidize the polyamic acid, thereby forming a polyimide film;

forming a device on the polyimide film; and

In particular, the method of manufacturing the flexible device may include a Low Temperature Polysilicon (LTPS) method, an ITO method, or an oxide method.

For example, a flexible device comprising an LTPS layer may be obtained by: an LTPS layer is formed by an LTPS film manufacturing method, which includes: formation of polyimide film containing SiO ₂ Is a barrier layer of (a);

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

performing a dehydrogenation annealing by heat-treating the deposited a-Si thin film at a temperature of 450 ℃ + -50 ℃; and

the a-Si thin film is crystallized by an excimer laser or the like.

The oxide thin film method may perform heat treatment at a lower temperature than a method using silicon, for example, the heat treatment temperature of the ITO TFT method may be 240 ℃ ± 50 ℃, and the heat treatment temperature of the oxide TFT method may be 350 ℃ ± 50 ℃.

EMBODIMENTS FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily perform the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

< preparation example 1> preparation of Compound of formula 1-1

The compound of formula A (40.0 g,190.6 mmol) was dissolved in THF (300 mL) under nitrogen and propylene oxide (5.5 g,95.3 mmol) was added and then cooled to-20deg.C. To this solution was introduced 4 parts at 10 minute intervals the compound of formula B (13.2 g,95.3 mmol). After 3 hours, hexane (300 ml) was added to give a solid. The solid obtained after filtration was washed with hexane/ethyl acetate (10/7) to prepare a compound of formula C (25.9 g, yield 87.0%).

MS[M+H] ⁺ ＝313

The compound of formula C (20 g,63.9 mmol) and the compound of formula D (10.2 g,32.0 mmol) were dispersed in glacial acetic acid (200 mL) and heated to 100deg.C. After 4 hours, the temperature was reduced to room temperature, and then ethanol was added to obtain a solid. The solid obtained after filtration was washed with water and ethanol to prepare a compound of formula E (26.8 g, 92.3% yield).

MS[M+H] ⁺ ＝909

After dispersing the compound of formula E (25 g,27.5 mmol) in NMP (N-methylpyrrolidone) (200 mL), palladium on carbon (0.75 g) was added and stirred under a hydrogen atmosphere for 16 hours. After completion of the reaction, water (200 mL) was added to the filtrate obtained after filtration to produce a solid. The solid obtained after filtration was recrystallized from NMP and ethyl acetate to prepare a compound of formula 1-1 (17.7 g, yield 75.9%).

MS[M+H] ⁺ ＝845

< preparation example 2> preparation of Compounds of formulas 1-2

A compound of formula G was prepared in the same manner as the method of preparing the compound of formula C, except that the compound of formula F was used instead of the compound of formula B in preparation example 1.

A compound of formula H is prepared in the same manner as the process for preparing the compound of formula E, except that a compound of formula G is used instead of a compound of formula C.

The compounds of formula 1-2 are prepared in the same manner as the process for preparing the compounds of formula 1-1, except that a compound of formula H is used instead of a compound of formula E.

MS[M+H] ⁺ ＝851

< preparation example 3> preparation of Compounds of formulas 1 to 5

A compound of formula J was prepared in the same manner as the process for preparing the compound of formula E, except that the compound of formula I was used instead of the compound of formula D in preparation example 1.

The compounds of formulas 1-5 were prepared in the same manner as the process for preparing the compounds of formulas 1-1, except that the compound of formula J was used instead of the compound of formula E.

MS[M+H] ⁺ ＝863

< preparation example 4> preparation of Compounds of formulas 1 to 9

A compound of formula L was prepared in the same manner as the method of preparing the compound of formula E, except that the compound of formula K was used instead of the compound of formula D in preparation example 1.

The compounds of formulas 1-9 are prepared in the same manner as the process for preparing the compounds of formulas 1-1, except that a compound of formula L is used instead of a compound of formula E.

MS[M+H] ⁺ ＝729

< preparation example 5> preparation of Compounds of formulas 1 to 13

A compound of formula N is prepared in the same manner as the method of preparing the compound of formula C, except that a compound of formula M is used instead of the compound of formula B in preparation example 1.

A compound of formula P is prepared in the same manner as the method of preparing the compound of formula E, except that a compound of formula N is used instead of a compound of formula C and a compound of formula O is used instead of a compound of formula D.

The compounds of formulas 1-13 are prepared in the same manner as the process for preparing the compounds of formulas 1-1, except that a compound of formula P is used instead of a compound of formula E.

MS[M+H] ⁺ ＝729

< preparation example 6> preparation of Compounds of formulas 1 to 14

A compound of formula R is prepared in the same manner as the process for preparing the compound of formula C, except that a compound of formula Q is used instead of the compound of formula B in preparation 1.

A compound of formula T is prepared in the same manner as the method of preparing the compound of formula E, except that a compound of formula R is used instead of a compound of formula C and a compound of formula O is used instead of a compound of formula D.

Compounds of formulas 1-14 are prepared in the same manner as the process for preparing compounds of formulas 1-1, except that a compound of formula T is used in place of a compound of formula E.

MS[M+H] ⁺ ＝731

< preparation example 7> preparation of Compounds of formulas 1 to 19

A compound of formula U is prepared in the same manner as the process for preparing the compound of formula E, except that a compound of formula N is used instead of a compound of formula C and a compound of formula K is used instead of a compound of formula D.

Compounds of formulas 1-19 are prepared in the same manner as the process for preparing compounds of formulas 1-1, except that a compound of formula U is used in place of a compound of formula E.

MS[M+H] ⁺ ＝731

Comparative example 1>6-FDA/TFMB

130g of DEAC (diethylacetamide) was charged into the reactor in a nitrogen stream, and then 0.0500mol of TFMB (2, 2' -bis (trifluoromethyl) benzidine) was added to dissolve it while maintaining the reactor temperature at 25 ℃. To the solution to which TFMB was added, 0.0500mol of 6-FDA (4, 4' - (hexafluoroisopropylidene) diphthalic anhydride) and 40g of DEAc were added and reacted for 48 hours to obtain a polyimide precursor solution.

< example 1>6-FDA/diamine of 1-1

200g of DEAC (diethylacetamide) was charged into the reactor in a nitrogen stream, and 0.0413mol of the diamine of formula 1-1 prepared in preparation example 1 was added to dissolve it while maintaining the reactor temperature at 25 ℃. To the solution to which the diamine of formula 1-1 was added, 0.0413mol of 6-FDA (4, 4' - (hexafluoroisopropylidene) diphthalic anhydride) and 60g of DEAC were added and reacted for 48 hours to obtain a polyimide precursor solution.

< example 2>6-FDA/diamine of 1-2

200g of DEAC (diethylacetamide) was charged into the reactor in a nitrogen stream, and 0.0413mol of the diamine of the formula 1-2 prepared in preparation example 2 was added to dissolve it while maintaining the reactor temperature at 25 ℃. To the solution to which the diamine of formula 1-2 was added, 0.0413mol of 6-FDA (4, 4' - (hexafluoroisopropylidene) diphthalic anhydride) and 60g of DEAC were added and reacted for 48 hours to obtain a polyimide precursor solution.

< example 3>6-FDA/diamine of 1-5

200g of DEAC (diethylacetamide) was charged into the reactor in a nitrogen stream, and 0.0413mol of the diamine of formulas 1 to 5 prepared in preparation example 3 was added to dissolve it while maintaining the reactor temperature at 25 ℃. To the solution to which the diamine of formulas 1 to 5 was added, 0.0413mol of 6-FDA (4, 4' - (hexafluoroisopropylidene) diphthalic anhydride) and 60g of DEAC were added and reacted for 48 hours to obtain a polyimide precursor solution.

< example 4>6-FDA/diamine of 1-19

200g of DEAC (diethylacetamide) was charged into the reactor in a nitrogen stream, and 0.0413mol of the diamine of formulas 1 to 19 prepared in preparation example 7 was added to dissolve it while maintaining the reactor temperature at 25 ℃. To the solution to which the diamine of formulas 1 to 19 was added, 0.0413mol6-FDA (4, 4' - (hexafluoroisopropylidene) diphthalic anhydride) and 60g DEAc were added and reacted for 48 hours to obtain a polyimide precursor solution.

Experimental example 1 ]

The viscosities of the polyimide precursor solutions prepared in examples 1 to 4 and comparative example 1 and the molecular weights of the polyamic acids were measured, and the results are shown in table 1 below. Viscosity was measured using Viscotek TDA302 and molecular weight was measured using Viscotek GPCmax VE 2001.

Experimental example 2

Each of the polyimide precursor solutions prepared in examples 1 to 4 and comparative example 1 was spin-coated on a glass substrate. The glass substrate coated with the polyimide precursor solution was put into an oven, heated at a rate of 5 deg.c/min and cured at 80 deg.c for 30 minutes, at 250 deg.c for 30 minutes and at 400 deg.c for 30 to 40 minutes to prepare a polyimide film. The characteristics of each film were measured, and the results are shown in table 1 below.

< modulus (GPa), tensile Strength (MPa), and elongation (%) >

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

TABLE 1

As can be seen from the results of table 1, the polyimide precursor solution containing the diamine according to the present invention may have a viscosity of 3000cP or more at a solid content concentration of 20 wt% or less, and thus a polyamic acid having a higher molecular weight is produced as compared to comparative example 1 using TFMB. Further, it can be seen that the polyimide film prepared from the polyamic acid having such a high molecular weight has improved mechanical strength as compared to the polyimide film of comparative example 1.

While the invention has been particularly shown and described with reference to specific embodiments thereof, it will be apparent to one skilled in the art that the specific description is of a preferred embodiment only and that the scope of the invention is not limited thereby. Accordingly, it is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.

Claims

1. A diamine having the structure of formula 1:

[ 1]

In the above-mentioned formula (1),

Z ₁ To Z ₈ Each independently is a carbon atom or a nitrogen atom, provided that Z ₁ To Z ₈ Not simultaneously being nitrogen atoms, R ₁ 、R ₂ 、R ₃ And R is ₄ Each independently selected from alkyl groups having 1 to 10 carbon atoms, haloalkyl groups having 1 to 10 carbon atoms, and aryl groups having 6 to 18 carbon atoms, n1, n2, n3, and n4 are each independently integers from 0 to 4, and X is a single bond or a functional group selected from the group consisting of: -O-, -S-, -C (=o) O-, -CH (OH) -, -S (=o) ₂ -、-Si(CH ₃ ) ₂ -, -CR 'R "-, -C (=O) NH-and combinations thereof, wherein R' and R" are each independently selectedFrom hydrogen atoms, alkyl groups having 1 to 10 carbon atoms and fluoroalkyl groups having 1 to 10 carbon atoms.

2. The diamine of claim 1 wherein Z ₁ To Z ₄ At least one of which must be a carbon atom, and Z ₅ To Z ₈ At least one of which must be a carbon atom.

3. The diamine of claim 1 wherein R ₁ And R is ₂ Each independently is an alkyl group having 1 to 5 carbon atoms or a haloalkyl group having 1 to 5 carbon atoms, or n1 and n2 are each independently 0.

4. The diamine of claim 1 wherein Z ₁ To Z ₄ All carbon atoms.

5. The diamine of claim 1 wherein Z ₁ To Z ₄ At least one of which is a nitrogen atom or Z ₅ To Z ₈ At least one of them is a nitrogen atom.

6. The diamine of claim 1 wherein Z ₁ To Z ₄ At least one of which is a nitrogen atom and Z ₅ To Z ₈ At least one of them is a nitrogen atom.

7. The diamine of claim 1 wherein the diamine of formula 1 is selected from compounds of formulas 1-1 to 1-20:

8. a polyimide precursor obtained by polymerizing a polymeric component comprising at least one diamine and at least one acid dianhydride, wherein the diamine comprises the diamine according to any one of claims 1 to 7.

9. A polyimide film produced by using the polyimide precursor according to claim 8.

10. A polyimide film manufactured by a method comprising: applying a polyimide precursor composition comprising the polyimide precursor of claim 8 onto a carrier substrate; and heating and curing the polyimide precursor composition.

11. A flexible device comprising the polyimide film according to claim 9 as a substrate.

12. A method for producing a flexible display, comprising:

applying a polyimide precursor composition comprising the polyimide precursor of claim 8 onto a carrier substrate;

forming a device on the polyimide film; and

13. The method for producing a flexible display according to claim 12, wherein the method comprises a low temperature polysilicon method, an ITO method, or an oxide method.

14. A process for preparing a diamine having the structure of formula 1, the process comprising the steps of:

reacting the compound of formula (iii) with a compound of formula (iv) to obtain a compound of formula (v); and

reducing the compound of formula (v):

Z _a to Z _d Each independently is a carbon atom or a nitrogen atom, provided that Z _a To Z _d Not simultaneously being nitrogen atoms, R ₁ 、R ₂ And R is _a Each independently selected from the group consisting of alkyl groups having 1 to 10 carbon atoms, haloalkyl groups having 1 to 10 carbon atoms, and aryl groups having 6 to 18 carbon atoms, n ₁ 、n ₂ And n is each independently an integer from 0 to 4, and X is a single bond or a functional group selected from the group consisting of: -O-, -S-, -C (=o) O-, -CH (OH) -, -S (=o) ₂ -、-Si(CH ₃ ) ₂ -CR 'R "-, -C (=o) NH-, and combinations thereof, wherein R' and R" are each independently selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, and a fluoroalkyl group having 1 to 10 carbon atoms.