KR20200042222A - Polyimide precursor and polyimide film manufactured by using same - Google Patents

Abstract

According to the present invention, a polyimide film manufactured by using a polyimide precursor can not only improve optical properties such as YI and light transmittance, but also have reduced changes in residual stress by moisture absorption, and thus can reduce the occurrence of cracks in an inorganic film that can be generated therefrom, thereby capable of being advantageously used in the manufacturing of flexible devices.

Description

Polyimide precursor and polyimide film using the same {POLYIMIDE PRECURSOR AND POLYIMIDE FILM MANUFACTURED BY USING SAME}

The present invention relates to a polyimide film and its precursor having improved optical properties.

In the display field, weight reduction and miniaturization of products are considered important, and since glass substrates currently being used are heavy, brittle and difficult to process continuously, plastic substrates that have the advantage of being light, flexible, and capable of continuous processing can be replaced by replacing glass substrates. Research is being actively conducted to apply the technology to cell phones, notebooks, PDAs, and the like.

In particular, polyimide (PI) resin is easy to synthesize, can make a thin film, and has the advantage of not needing a crosslinker for curing. Recently, it has been integrated into semiconductor materials such as LCD and PDP due to the light weight and precision of electronic products. As a result, many studies have been conducted to use PI for a flexible plastic display board having light and flexible properties.

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

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

The problem to be solved by the present invention is to provide a polyimide precursor for producing a polyimide film with improved optical properties.

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

In addition, another object of the present invention is to provide a flexible device comprising the polyimide film and a manufacturing process thereof.

In addition, another object of the present invention is to provide a diamine having a novel structure and a method for manufacturing the polyimide film having improved optical properties.

In order to solve the problems of the present invention,

A polyimide precursor obtained by polymerizing a polymerization component comprising at least one diamine and at least one acid dianhydride,

It provides a polyimide precursor that the diamine in the polymerization component includes a diamine represented by the following formula (1).

[Formula 1]

In Chemical Formula 1,

R ₁ and R ₂ are each independently an alkyl group having 1 to 3 carbon atoms, a haloalkyl group having 1 to 3 carbon atoms, or a halogen atom,

n and m are each independently an integer of 1 to 4.

According to an embodiment, R ₁ and R ₂ may each independently be a fluoroalkyl group having 1 to 3 carbon atoms.

According to one embodiment, the polymerization component may include a diamine or an acid dianhydride having the structure of Formula 2 below.

[Formula 2]

In Chemical Formula 2,

R ₃ . Each of R ₄ is independently a monovalent organic group having 1 to 20 carbon atoms, and h is an integer of 3 to 200.

According to one embodiment, the compound of Formula 2 may be included in 5 to 50% by weight relative to the total weight of the polymerization component.

According to one embodiment, the Chemical Formula 2 may be a diamine having the structure of Chemical Formula 2-1.

[Formula 2-1]

In Chemical Formula 2-1,

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

In order to solve other problems of the present invention,

Applying a polyimide precursor composition comprising the polyimide precursor on a carrier substrate; And

A polyimide film prepared by a method comprising heating and curing the polyimide precursor composition may be provided.

According to one embodiment, the residual stress immediately after curing of the polyimide precursor composition may be 40 MPa or less.

According to one embodiment, after the polyimide film is left at 25 ° C and 50% humidity for 3 hours, a change value of the residual stress may be 5 MPa or less.

According to one embodiment, the yellowness of the polyimide film may be 15 or less.

The present invention also provides a flexible device comprising the polyimide film as a substrate.

The present invention also

Applying the polyimide precursor composition on a carrier substrate;

Heating the polyimide precursor composition to imidize polyamic acid to form a polyimide film;

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 on which the device is formed from the carrier substrate.

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

The present invention also provides a diamine having the structure of Formula 1 below.

[Formula 1]

In Chemical Formula 1,

R ₁ and R ₂ are each independently an alkyl group having 1 to 3 carbon atoms, a haloalkyl group having 1 to 3 carbon atoms, or a halogen atom,

n and m are each independently an integer of 1 to 4.

According to one embodiment, the ¹ HNMR of the diamine compound is δ5.5 ~ 5.9 (s, 4H), δ6.8 ~ 6.4 (d, 2H), δ6.97 ~ 7.0 (s, 2H), δ7.04 ~ Peaks can be exhibited at 7.1 (d, 2H), δ 7.4 to 7.52 (d, 4H), δ 7.99 to 8.01 (d, 4H).

The present invention also provides a method for preparing a diamine compound of Formula 1-1 by reacting a compound of Formula A with a compound of Formula B.

In the above formula,

R is an alkyl group having 1 to 3 carbon atoms, a haloalkyl group having 1 to 3 carbon atoms, or a halogen atom.

The present invention not only can improve the optical properties such as YI and light transmittance by preparing a polyimide film using a polyimide precursor prepared using a diamine having the structure of Formula 1, but also to absorb moisture in the polyimide film. Due to the small change in residual stress, the cracking of the inorganic film, which can occur therefrom, can be reduced, which can be usefully used in the manufacture of flexible devices.

1 is a ¹ H-NMR measurement results of a diamine compound prepared according to an embodiment.

The present invention can be applied to various transformations and can have various embodiments, and specific embodiments will be 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 should be understood to include all conversions, equivalents, and substitutes included in the spirit and scope of the present invention. In the description of the present invention, when it is determined that a detailed description of known technologies related to the present invention may obscure the subject matter of the present invention, the detailed description will be omitted.

All compounds or organic groups herein 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, a hydroxyl group , Substituted with a substituent selected from the group consisting of alkoxy groups having 1 to 10 carbon atoms, carboxylic acid groups, aldehyde groups, epoxy groups, cyano groups, nitro groups, amino groups, sulfonic acid groups and derivatives thereof.

The present invention is a polyimide precursor obtained by polymerizing a polymerization component comprising at least one diamine and at least one acid dianhydride,

It provides a polyimide precursor that the diamine in the polymerization component includes a diamine represented by the following formula (1).

[Formula 1]

In Chemical Formula 1,

R ₁ and R ₂ are each independently an alkyl group having 1 to 3 carbon atoms, a haloalkyl group having 1 to 3 carbon atoms, or a halogen atom (-F, -Cl, -Br, -I), preferably fluorine having 1 to 3 carbon atoms. It may be a roalkyl group,

n and m are each independently an integer of 1 to 4.

The present invention can provide a transparent polyimide film without requiring a special solvent combination by providing a polyimide precursor containing the diamine of Formula 1 as a polymerization component. In addition, it is possible to provide a polyimide film having a low residual stress generated between the inorganic film, excellent chemical resistance, and a small effect on increasing the YI value and decreasing light transmittance due to oxygen concentration during the curing process. .

Substituents of Formula 1 may have more amorphous properties by reducing the intermolecular packing density of the polyimide, thereby improving optical properties (eg, YI value and transmittance). Further, preferably, by having a fluoroalkyl group as a substituent, the water absorption of the polyimide film can be improved.

In the case of a polyimide containing DDS ((diaminodiphenyl) sulfone), the residual stress changes according to the standing time after the TFT process are severe, and the inorganic stress crack may occur due to the residual stress change. On the other hand, the diamine of Formula 1 includes a fluoroalkyl group as a substituent, so that the water absorption according to the standing time can be significantly reduced, and thus the change in residual stress can also be reduced.

According to one embodiment, the polyimide film containing the diamine of Formula 1 may have a residual stress immediately after curing of 40 MPa or less, and the residual stress change value after leaving the polyimide film at 25 ° C. and 50% humidity for 3 hours. This may be 5 MPa or less.

The diamine of Formula 1 may be synthesized by the same reaction as in Scheme 1 below.

[Scheme 1]

In the above formula,

R is an alkyl group having 1 to 3 carbon atoms, a haloalkyl group having 1 to 3 carbon atoms, or a halogen atom.

According to one embodiment, the reaction is as shown in Scheme 2 below,

a) dissolving a compound of Formula A and a compound of Formula B-1 in THF (tetrahydrofuran) in a nitrogen atmosphere;

b) adding potassium carbonate dissolved in distilled water to the THF solution and heating while stirring;

c) adding palladium tetratriphenylphosphine ((Ph ₃ P) ₄ Pd) while refluxing the solution prepared in step b) and stirring to reflux; And

d) After the reaction type, the temperature may be lowered to room temperature, and then ethane may be added to obtain a compound represented by Chemical Formula 1-2.

[Scheme 2]

In the above formula,

R is an alkyl group having 1 to 3 carbon atoms, a haloalkyl group having 1 to 3 carbon atoms, or a halogen atom.

According to one embodiment, the diamine of Formula 1 has ¹ HNMR of δ5.5 ~ 5.9 (s, 4H), δ6.8 ~ 6.4 (d, 2H), δ6.97 ~ 7.0 (s, 2H), δ7. 04 ~ 7.1 (d, 2H), δ 7.4 ~ 7.52 (d, 4H), δ 7.99 ~ 8.01 (d, 4H) can show peaks, and the result of the peaks is a phenyl group directly bonded to the diphenyl sulfone structure. And may indicate that a substituent is present on the directly bonded phenyl group.

The polyimide precursor according to the present invention may include a diamine or an acid dianhydride having the structure of Formula 2 as a polymerization component:

[Formula 2]

In Chemical Formula 2,

R ₃ and R ₄ are each independently 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 Formula 2-1.

[Formula 2-1]

In Chemical Formula 2-1,

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

The compound of Formula 2 may be included in an amount of 5 to 50% by weight based on the total weight of the polymerization component, preferably 10 to 20% by weight relative to the total weight of the total polymerization component.

When the polymerization component including the structure of Formula 2 is excessively added with respect to the total weight, mechanical properties such as modulus of the polyimide may be deteriorated, and film strength may be reduced, resulting in tearing of the film in the process. Physical damage may occur. In addition, when the diamine having the structure of Formula 2 is excessively added, Tg derived from the polymer having the siloxane structure may appear, from which Tg appears at a low process temperature of 350 ° C. or lower, and higher than 350 ° C. During the inorganic film deposition process, wrinkles may occur on the film surface due to the flow phenomenon of the polymer, and the inorganic film may be cracked.

In general, in the case of a polyimide containing 10% by weight or more of a diamine or an acid dianhydride containing a silicone oligomer structure as shown in Chemical Formula 2, the effect of reducing residual stress may be increased, and in a composition higher than 50% by weight Tg is lower than 390 ℃ heat resistance may be lowered.

On the other hand, the polyimide according to the present invention can maintain a Tg of 390 ° C. or higher despite containing a silicone oligomer in an amount of 10% by weight or more based on the total polymerization component. Therefore, while maintaining the glass transition temperature at 390 ° C or higher, a reduction effect of residual stress due to the silicone oligomer structure can also be obtained.

The molecular weight of the silicone oligomer structure contained in the diamine or acid dianhydride having the structure of Formula 2 may be 4000 g / mol or more, wherein the molecular weight means the weight average molecular weight, and the molecular weight calculation is performed using NMR analysis or an acid group titration method. A method of calculating the equivalent weight of a reactor such as amine or dianhydride can be used.

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

According to the present invention, the size of the silicon oligomer domains distributed in the polyimide matrix is nano-sized, for example, 1 nm to 50 nm, or 5 nm to 40 nm, or 10 nm to 30 nm, so that it has a continuous phase, thus maintaining heat resistance and mechanical properties. Residual stress can be minimized. In the case of not having such a continuous phase, the residual stress may be reduced, but the heat resistance and mechanical properties are significantly reduced, making it difficult to use in the process.

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

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

Therefore, although the present invention is a silicone oligomer having a high molecular weight, it can be uniformly distributed in the polyimide matrix without phase separation, so that haze characteristics are lowered to obtain a polyimide having more transparent characteristics, as well as a silicone oligomer structure. Because it exists as a continuous phase, the mechanical strength and stress relieving effect of polyimide can be improved more efficiently. From these properties, the composition according to the present invention can provide a flat polyimide film by reducing the thermal and optical properties, as well as the phenomenon of substrate warping after coating-curing.

In the present invention, by inserting the silicone oligomer structure into the polyimide structure, the modulus strength of the polyimide can be appropriately improved, and stress caused by external force can also be relieved. At this time, the polyimide containing the silicone oligomer structure may exhibit polarity, and phase separation may occur due to a polarity difference with the polyimide structure not containing the siloxane structure, and thereby, the siloxane structure is unevenly distributed throughout the polyimide structure. Can be. In this case, it is difficult to exhibit a property improvement effect such as strength improvement and stress relaxation effect of the polyimide due to the siloxane structure, and haze increases due to phase separation, so that the transparency of the film may deteriorate. In particular, when the diamine containing the siloxane structure has a high molecular weight, the polarity of the polyimide prepared therefrom may be more apparent, and the phase separation phenomenon between the polyimides may be more pronounced. At this time, when using a siloxane diamine having a low molecular weight structure, a large amount must be added in order to exhibit an effect such as stress relaxation, which may cause process problems such as Tg generation at a low temperature. Due to this, physical properties of the polyimide film may be deteriorated. Accordingly, when a high molecular weight siloxane diamine is added, a relaxation segment may be largely formed in the molecule, and thus, a stress reduction effect may be effectively exhibited even in a small amount compared to the addition of a low molecular weight. Therefore, the present invention can be more evenly distributed without phase separation on the polyimide matrix by using the compound of Formula 2 having the siloxane structure having the high molecular weight.

According to one embodiment, as the acid dianhydride used to polymerize the polyimide precursor, tetracarboxylic dianhydride may be used,

For example, as the tetracarboxylic dianhydride, intramolecular aromatic, cycloaliphatic, or aliphatic tetravalent organic groups, or combinations thereof, aliphatic, cycloaliphatic or aromatic tetravalent organic groups can cross each other through a crosslinked structure. Tetracarboxylic dianhydrides containing linked tetravalent organic groups can be used. Preferably, monocyclic or polycyclic aromatic, monocyclic or polycyclic alicyclic, or two or more of these may include an acid dianhydride having a structure connected by a single bond or a functional group. Or, a tetracarboxylic acid containing a tetravalent organic group having a rigid structure such as a heterocyclic ring structure in which a ring structure such as aromatic or cycloaliphatic is single or fused, or a structure connected by a single bond. It may contain dianhydride.

For example, the tetracarboxylic dianhydride may include a tetravalent organic group having the structure of Formulas 3a to 3e:

[Formula 3a]

[Formula 3b]

[Formula 3c]

[Formula 3d]

[Formula 3e]

In Formulas 3a to 3e, R ₁₁ to R ₁₇ are each independently a halogen atom selected from -F, -Cl, -Br and -I, hydroxyl group (-OH), thiol group (-SH), nitro A group (-NO ₂ ), 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, or an aryl group having 6 to 20 carbon atoms,

The 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, a6 and a9 are each independently an integer from 0 to 3 , And a7 and a8 may be each independently an integer of 0 to 7,

The A ₁₁ and A ₁₂ are each independently a single bond, -O-, -CR ₁₈ R _19- , -C (= O)-, -C (= O) NH-, -S-, -SO _2- , It may be selected from the group consisting of phenylene groups and combinations thereof, wherein R ₁₈ and R ₁₉ 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. It can be.

Alternatively, the tetracarboxylic dianhydride may include a tetravalent organic group selected from the group consisting of the following Chemical Formulas 4a to 4n.

One or more hydrogen atoms in the tetravalent organic group of the formulas 4a to 4n are halogen atom selected from -F, -Cl, -Br and -I, hydroxyl group (-OH), thiol group (-SH), nitro group ( -NO ₂ ), 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, or an aryl group having 6 to 20 carbon atoms. For example, the halogen atom may be fluoro (-F), the halogenoalkyl group is a fluoroalkyl group having 1 to 10 carbon atoms containing a fluoro atom, fluoromethyl group, perfluoroethyl group, trifluoro It may be selected from methyl groups, and the alkyl group may be selected from methyl groups, ethyl groups, propyl groups, isopropyl groups, t-butyl groups, pentyl groups, and hexyl groups, and the aryl groups are selected from phenyl groups and naphthalenyl groups. It may be, and more preferably, it may be a substituent containing a fluoro atom such as a fluoro atom and a fluoroalkyl group.

Alternatively, in the tetracarboxylic dianhydride, an aromatic ring or an aliphatic structure is a structure in which each ring structure is rigid, that is, a single ring structure, a structure in which each ring is bonded by a single bond, or each ring It may be one containing a tetravalent organic group containing a heterocyclic structure directly connected.

According to one embodiment, in the polymerization of the polyimide precursor, one or more diamines may be further included in addition to the formula 1 diamine, for example, a monocyclic or polycyclic aromatic divalent organic group having 6 to 24 carbon atoms, and 6 to 18 carbon atoms. A monocyclic or polycyclic alicyclic divalent organic group, or a diamine containing a divalent organic group structure selected from a divalent organic group comprising a structure in which two or more of them are connected by a single bond or a functional group may be included, Or, a ring structure compound such as aromatic or cycloaliphatic is selected from a divalent organic group having a rigid structure such as a monocyclic or fused heterocyclic ring structure or a structure connected by a single bond. You can.

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

[Formula 5a]

[Formula 5b]

[Formula 5c]

[Formula 5d]

[Formula 5e]

In the above formulas 5a to 5e,

R ₂₁ to R ₂₇ are each independently a halogen atom selected from -F, -Cl, -Br and -I, hydroxyl group (-OH), thiol group (-SH), nitro group (-NO ₂ ), cyan It may be selected from the group consisting of a furnace 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,

In addition, A ₂₁ and A ₂₂ are each independently a single bond, -O-, -CR'R "-(where R 'and R" are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms (for example, Methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, tert-butyl group, pentyl group, etc.) and haloalkyl group having 1 to 10 carbon atoms (for example, trifluoromethyl group, etc.) Will be), -C (= O)-, -C (= O) O-, -C (= O) NH-, -S-, -SO-, -SO2-, -O [CH ₂ CH ₂ O] y- (y is an integer from 1 to 44), -NH (C = O) NH-, -NH (C = O) O-, monocyclic or polycyclic cycloalkylene group having 6 to 18 carbon atoms (for example, , Cyclohexylene group, etc., monocyclic or polycyclic arylene group having 6 to 18 carbon atoms (for example, phenylene group, naphthalene group, fluorenylene group, etc.), and combinations thereof. And

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 integers from 0 to 4, and b7 and b8 are each independently 0 to 0 It is an integer of 9, and b6 and b9 are each independently an integer of 0-3.

Alternatively, the diamine may include a divalent organic group selected from the group consisting of the following Chemical Formulas 6a to 6p.

At least one hydrogen atom in the divalent organic group of the formulas 6a to 6p is a halogen atom selected from -F, -Cl, -Br and -I, a hydroxyl group (-OH), a thiol group (-SH), a nitro group ( -NO ₂ ), 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, or an aryl group having 6 to 20 carbon atoms. For example, the halogen atom may be fluoro (-F), the halogenoalkyl group is a fluoroalkyl group having 1 to 10 carbon atoms containing a fluoro atom, fluoromethyl group, perfluoroethyl group, trifluoro It may be selected from methyl groups, and the alkyl group may be selected from methyl groups, ethyl groups, propyl groups, isopropyl groups, t-butyl groups, pentyl groups, and hexyl groups, and the aryl groups are selected from phenyl groups and naphthalenyl groups. It may be, and more preferably, it may be a substituent containing a fluoro atom such as a fluoro atom and a fluoroalkyl group.

Alternatively, the diamine may include a divalent organic group forming a rigid chain structure of an aromatic ring or an aliphatic structure, for example, a single ring structure, a structure in which each ring is bonded by a single bond, or Each ring may include a divalent organic group structure including a fused heterocyclic ring structure.

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

According to one embodiment of the present invention, the molar ratio of the total content of the tetracarboxylic dianhydride and the content of diamine may be preferably reacted at 1: 0.99 to 0.99: 1, preferably 1: 0.98 to 0.98: 1. .

The polymerization reaction of the acid dianhydride and the diamine-based compound can be carried out according to a polymerization method of a conventional polyimide or a precursor thereof, such as solution polymerization.

Examples of the organic solvent that can be used in the polyamic acid polymerization reaction include gamma-butyrolactone, 1,3-dimethyl-2-imidazolidinone, methyl ethyl ketone, cyclohexanone, cyclopentanone, and 4-hydroxy-4. Ketones such as -methyl-2-pentanone; Aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; 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 , Glycol ethers such as dipropylene glycol diethyl ether and triethylene glycol monoethyl ether (cellosolve); 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 Dimethylpropionamide (DMPA), diethylpropionamide (DEPA), dimethylacetamide (DMAc), N, N-diethylacetamide, dimethylformamide (DMF), diethylformamide (DEF), N -Methylpyrrolidone (NMP), N-ethylpyrrolidone (NEP), N, N-dimethylmethoxyacetamide, dimethylsulfoxide, pyridine, dimethylsulfone, hexamethylphosphoramide, tetramethylurea, N- Methylcaprolactam, tetrahydrofuran, m-dioxane, P-dioxane, 1,2-dimethoxyethane, bis (2-methoxyethyl) ether, 1,2-bis (2-methoxyethoxy) ethane , 'S [2- (2-methoxyethoxy)] ether, amide Ek (Equamide) M100, amides Ek (Equamide) and the like B100, there is a singly or as mixtures of two or more thereof may be used of these.

According to an embodiment, a solvent having a positive distribution coefficient LogP may be used as an organic solvent for polymerizing the polymerization component. By using an organic solvent in which LogP is a positive number, Tg can be maintained at a high temperature of 390 ° C or higher even in a composition in which methylphenylsilicone oligomer is contained in an amount of 10% by weight or more.

In addition, the organic solvent having a positive partition coefficient as described above may reduce cloudiness caused by phase separation due to polarity differences between a flexible polyimide repeating structure and a polyimide structure including a siloxane structure such as a silicone oligomer. have. Conventionally, two types of organic solvents have been used to solve the phase separation, but it is possible to reduce the cloudiness by using the organic solvents as described above, so that a more transparent polyimide film can be produced.

In order to solve the above-mentioned problem, there is a method of mixing and using a polar solvent and a non-polar solvent, but in the case of a polar solvent, there is a tendency of high volatility, and thus problems such as volatilization in advance in the manufacturing process may occur. Not only may problems such as deterioration of reproducibility, but the phase separation problem may not be completely improved, and the haze of the prepared polyimide film may be increased and transparency may be reduced.

More specifically, by using a solvent containing a structure in which the molecules of the solvent have an amphiphilic structure, it is possible to solve not only a process problem due to the use of a polar solvent, but also one type due to the molecular structure having an amphiphilic property. Even if only a solvent is used, the polyimide can be evenly distributed, which makes it very suitable for solving problems caused by phase separation, and thus, it is possible to provide a polyimide having a significantly improved haze property.

When the distribution coefficient value is positive, it means that the polarity of the solvent is hydrophobic. According to the research of the present inventors, it can be seen that when the polyimide precursor composition is prepared using a specific solvent having a positive distribution coefficient value, the edge back phenomenon is improved. there was. In addition, the present invention can control the edge back phenomenon of the solution without using additives that control the surface tension of the material such as a leveling agent and the smoothness of the coating film by using a solvent in which Log P has a positive number as described above, This does not use additional additives such as additives, so it is possible to remove the quality and process problems such as the presence of low-molecular substances in the final product, as well as more efficiently to form a polyimide film having uniform properties. There is.

For example, in the process of coating the polyimide precursor composition on the glass substrate, an edge back phenomenon may occur due to shrinkage of the coating layer during curing or under the condition of leaving the coating solution in a humidity condition. The edge back phenomenon of such a coating solution may cause a variation in the thickness of the film, resulting in the film being cut or a corner being broken when cutting due to a lack of flex resistance of the film, resulting in poor process workability and reduced yield. Problems may arise.

In addition, when a fine foreign matter having polarity is introduced into the polyimide precursor composition applied on the substrate, in the polyimide precursor composition including a polar polar solvent having a negative log P, the position of the foreign matter is based on the polarity of the foreign matter. As a result, sporadic cracking or thickness change of coating may occur, but when a hydrophobic solvent having a positive log P is used, even when fine foreign matter having polarity is introduced, the occurrence of thickness variation due to cracking of the coating is reduced or suppressed. Can be.

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

[Equation 1]

Edge percentage (%) = [(A-B) / A] Υ100

In the above formula 1,

A: The area in the state where the polyimide precursor composition is completely coated on the substrate (100 mm Υ 100 mm),

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

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 thickness of the edge may be thickened by starting to roll from the edge.

After coating the polyimide precursor composition according to the present invention on a substrate for 10 minutes or more, for example 10 minutes or more, for example, 40 minutes or more, the edge percentage of the coated resin composition solution after being left in a humidity condition is 0.1. % 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% , 80% in each humidity condition, for example, even after standing for 10 to 50 minutes at a humidity condition of 50% may exhibit a very small edge percentage of less than 0.1%, preferably 0.05%, more preferably almost It can show an edge percentage close to 0%.

The edge percentage 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 Is cured after being left for 10 to 50 minutes at a humidity condition in the range of 40% to 80%, that is, at a humidity condition of 40%, 50%, 60%, 70%, and 80%, for example, at a humidity condition of 50%. The polyimide film may have an edge percentage of 0.1% or less, that is, an edge-back phenomenon may or may not occur even in a curing process by heat treatment. Specifically, an edge close to 0.05%, more preferably almost 0% It can indicate the percentage.

By solving this edge back phenomenon, the polyimide precursor composition according to the present invention can obtain a polyimide film having more uniform characteristics, thereby improving the yield of the manufacturing process.

In addition, the density of the solvent according to the present invention is ASTM as determined using the standard measurement method D1475, 1g / cm ³ can be less than a density of 1 g / If having a cm ³ or more values, it may increase the relative viscosity of the process the Efficiency can be reduced.

The LogP is a positive solvent, for example, N, N-diethylacetamide (N, Ndiethylacetamide, DEAc), N, N-diethylformamide (N, N-diethylformamide, DEF), N-ethylpyrroli It may be one or more selected from money (N-ethylpyrrolidone, NEP), dimethyl propionamide (DMPA) and diethyl propionamide (DEPA).

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

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

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

In addition, in the case of synthesizing polyamic acid or polyimide, in order to inactivate excess polyamino group or acid anhydride group, a molecular terminal is reacted with dicarboxylic acid anhydride or monoamine to further add a terminal sealant to seal the polyimide end. You can.

The method for reacting the tetracarboxylic dianhydride with diamine can be carried out according to a conventional polyimide precursor polymerization production method such as solution polymerization. Specifically, after diamine is dissolved in an organic solvent, it can be prepared by adding a tetracarboxylic dianhydride to the resultant mixed solution to polymerize it.

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

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

It is preferable that the polyamic acid solution prepared according to the above-described manufacturing method contains solids in an amount to allow the composition to have an appropriate viscosity in consideration of processability such as coatability 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 when it has such a form, for example, when a polyimide precursor is synthesized in an organic solvent, the solution is a reaction solution obtained. It may be itself, or this reaction solution may be diluted with another solvent. Moreover, when a polyimide precursor was obtained as a solid powder, you may melt | dissolve this in the organic solvent and make it 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% by weight, preferably 10 to 25% by weight, more preferably 10 to 20% by weight % Or less.

Alternatively, the polyimide precursor composition may be adjusted to have a viscosity of 3,000 cP or more, or 4,000 cP or more, and the viscosity of the polyimide precursor composition is 10,000 cP or less, preferably 9,000 cP or less, more preferably 8,000 cP It is preferable to adjust to have the following viscosity. When the viscosity of the polyimide precursor composition exceeds 10,000 cP, the efficiency of defoaming decreases during processing of the polyimide film, and thus, not only the process efficiency, but also the prepared film has poor surface roughness due to the generation of bubbles, resulting in poor electrical, optical, and mechanical properties. It may degrade.

Subsequently, a transparent polyimide film may be prepared by imidizing the polyimide precursor obtained as a result of the polymerization reaction using a chemical or thermal imidization method.

According to one embodiment, the step of applying a polyimide precursor composition on a carrier substrate; And

A polyimide film may be prepared by a method including heating and curing the polyimide precursor composition.

At this time, as the carrier substrate, a glass, metal substrate, or plastic substrate may be used without particular limitation, and among them, excellent thermal and chemical stability during the imidation and curing process for the polyimide precursor, without additional release agent treatment, A glass substrate that can be easily separated without damage to the polyimide-based film formed after curing may be desirable.

In addition, the coating process may be performed according to a conventional coating method, specifically, spin coating method, bar coating method, roll coating method, air-knife method, gravure method, reverse roll method, kiss roll method, doctor blade method, Spray method, immersion method or 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 capable of increasing the imidation rate of polyimide.

In addition, the polyimide precursor composition may be applied on the substrate in a thickness range that allows the final manufactured polyimide film to have a suitable thickness for a display substrate.

Specifically, it may be applied in an amount to make the thickness of 8 to 30㎛. After application of the polyimide precursor composition, a drying process for removing the solvent present in the polyimide precursor composition may be selectively performed prior to the curing process.

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

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

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

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

In addition, the transmittance at 450 nm of the polyimide film may be 75% or more, the transmittance at 550 nm may be 85% or more, and the transmittance at 630 nm may be 90% or more.

The polyimide film may have high heat resistance, for example, a thermal decomposition temperature (Td_1%) in which mass loss is 1% may be 500 ° C or higher.

The polyimide film prepared as described above may have a modulus of 3.5 GPa or less and an elongation of 20% or more. If the modulus (modulus of elasticity) is less than 0.1 GPa, the film has low rigidity and is easily fragile to external impact. When the modulus of elasticity exceeds 3.5 GPa, the coverlay film has excellent stiffness but cannot secure sufficient flexibility. You can.

In addition, the polyimide film according to the present invention may have excellent thermal stability according to temperature change, for example, a thermal expansion coefficient after a heating and cooling process n + 1 times in the temperature range of 100 ° C to 350 ° C is -10 It may have a value of 100 to 100 ppm / ℃, preferably a value of -7 to 90 ppm / ℃, more preferably 80 ppm / ℃ or less (where 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 retardation (R _th ) in the thickness direction of -150 nm to +150 nm, preferably -130 nm to +130 nm, thereby improving visibility. .

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

In addition, the present invention,

Applying the polyimide precursor composition on a carrier substrate;

Heating the polyimide precursor composition to imidize polyamic acid to form a polyimide film;

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 on which the device is formed 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 blocking layer containing SiO ₂ on the polyimide film;

Depositing an a-Si (Amorphous silicon) thin film on the blocking layer;

A dehydrogen 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, a flexible device including an LTPS layer can be obtained by peeling a carrier substrate and a polyimide film by laser peeling or the like.

The oxide thin film process may be heat treated at a lower temperature than the 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 may be 350 ° C ± 50 ° C. Can be

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art to which the present invention pertains can easily practice. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein.

<Production Example 1>

Diamine of Formula 1-3 was prepared by the same reaction as in Scheme 3 below.

Specifically, the following formula A (50 g, 106 mmol) and formula B-2 (25.3 g, 106 mmol) were dissolved in tetrahydrofuran (300 mL) in a nitrogen atmosphere, and potassium carbonate (58.5 g, 424 mmol) was dissolved in water (150 mL). It was added and heated while stirring. In reflux, palladium tetratriphenylphosphine (1.22 g, 1.06 mmol) was added and stirred under reflux for 5 hours. After the reaction was completed, the temperature was reduced to room temperature and ethanol was added to obtain a solid. The solid obtained after filtration was washed with water and ethanol to prepare a diamine of Chemical Formula 1-3 below in 85% yield (48.3 g). The results of ¹ HNMR analysis of the prepared formula 1-3 diamine are shown in FIG. 1.

[Scheme 3]

¹ HNMR (500MHz, DMSO): δ5.78 (s, 4H), 6.81 (d, 2H), 6.99 (s, 2H), 7.05 (d, 4H), 7.50 (d, 4H), 7.99 (d, 4H) )

<Comparative Example 1> PMDA / DDS

After filling 50 g of DEAc (Diethylacteamide) in a reactor with flowing nitrogen air, dissolve by adding 0.0458 mol of 4,4'-DDS (4,4'-diaminodiphenyl sulfone) at the same temperature while maintaining the temperature of the reactor at 25 ° C. Ordered. To the solution to which the DDS was added, 0.0458 mol of PMDA (pyromellitic dianhydride) was added together with 50 g of DEAc, and then reacted for 48 hours to prepare a polyimide precursor solution.

<Comparative Example 2> BPDA / DDS

After filling 40 g of DEAc in a reactor in which a nitrogen stream was flowing, 0.03395 mol of 4,4'-DDS was added and dissolved at the same temperature while maintaining the temperature of the reactor at 25 ° C. To the solution to which DDS was added, 0.03395 mol of BPDA (3,3 ', 4,4'-biphenyltetracarboxylic dianhydride) was added with 46 g of DEAc, followed by reaction for 48 hours to prepare a polyimide precursor solution .

<Example 1> PMDA / Formula 1-3 diamine

After filling 100 g of DEAc in a reactor through which a nitrogen stream flows, 0.04585 mol of diamine of Formula 1-3 prepared in Preparation Example 1 is dissolved at the same temperature while maintaining the temperature of the reactor at 25 ° C. A polyimide precursor solution was prepared by adding 0.04585 mol of PMDA (pyromellitic dianhydride) with DEAc 62g to the solution added with Formula 1-3 diamine and reacting for 48 hours.

<Example 2> BPDA / Formula 1-3 diamine

After filling 80 g of DEAc in a reactor through which a nitrogen stream flows, 0.03395 mol of diamine of Formula 1-3 prepared in Preparation Example 1 is dissolved at the same temperature while maintaining the temperature of the reactor at 25 ° C. A polyimide precursor solution was prepared by adding 0.03395 mol of BPDA (3,3 ', 4,4'-biphenyltetracarboxylic dianhydride) to the solution in which the formula 1-3 was added together with DEAc 52g and reacting for 48 hours.

<Experimental Example 1>

Each polyimide precursor solution prepared in Examples 1 and 2 and Comparative Examples 1 and 2 was spin coated on a glass substrate. The glass substrate coated with the polyimide precursor solution was placed in an oven and heated at a rate of 5 ° C./min.The curing process was performed by maintaining 30 minutes at 80 ° C., 30 minutes at 250 ° C., and 30 to 40 minutes at 410 ° C. A polyimide film was prepared. Table 1 shows the physical properties of each film.

<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 is based on JIS K 7105. Transmittance (model name HR-100, manufactured by Murakami Color Research Laboratory) is used to measure transmittance for 450nm, 550nm and 630nm wavelengths.

It was.

<Thickness direction retardation (Rth)>

The thickness direction retardation (Rth) was measured using Axoscan. Cut the film to a certain size, measure the thickness, and then measure the phase difference with Axoscan to input the measured thickness while compensating in the C-plate direction to compensate for the phase difference value.

<Pyrolysis temperature (Td1%)>

TGA was used to measure the temperature at a weight reduction rate of 1% of the polymer in a nitrogen atmosphere.

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

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

<Residual stress measurement>

On a 4in silicon wafer with a thickness of 525um, the wafer's [bending amount] was measured in advance using a residual stress measuring device measuring device (TENCOR FLX2320), and a resin composition was applied with a spin coater (manufactured by Koyo Lindberg). Using, a heat curing treatment of 250 ° C 30min and 400 ° C 60min under a nitrogen atmosphere was carried out, and after curing, a silicon wafer with a resin film having a thickness of 10um was prepared. The residual stress generated between the silicon wafer and the resin film was measured by measuring the amount of warpage of this wafer using the above-described residual stress measuring apparatus.

Then, the residual stress was measured after leaving the same polyimide film for 3 hours at 25 ° C and 50% humidity.

sample Comparative Example 1
PMDA_DDS Comparative Example 2
BPDA_DDS Example 1
PMDA_Formula 1-3 Example 2
BPDA_Formula 1-3 Sol. Con. (wt%) 22.6 21.5 18.9 18.9 Viscosity (cps) 3424 3020 3320 3320 Curing condition (5 ℃ / min)
80 ℃ 30min → 250 ℃ 30min 400 ℃ 30min 400 ℃ 40min 400 ℃ 40min 400 ℃ 40min Thickness (㎛) 9.8 9.53 9.4 9.68 YI 18.2 4.3 12.8 3.2 Haze 0.1 0.27 0.4 0.2 Rth (nm) 550 nm 200 100 125 35 Transmittance
(%) 450 nm 71.4 83.2 77.5 85.4 550 nm 84.3 89.9 88.7 90.1 630 nm 86.1 90.3 93.3 90.7 Td1% (℃) 495 527 505 537 Modulus (Gpa) 2.3 2.9 2.6 3.2 Tensile strength (Mpa) 125 132 110 130 Strain (%) 90 50 65 45 Immediately after curing the residual stress (Mpa) 40 42 36 39 Left for 3h after curing residual stress (Mpa)
@ 25 ℃ 50% 31 30 33 36

From the results of Table 1, it can be seen that in the case of the polyimide film according to the present invention, the change in residual stress due to moisture appears very low. In addition, it can be seen that compared to using DDS diamine under the same acid dianhydride composition, optical properties such as YI, thickness direction retardation (R _th ), and transmittance are also improved.

Since the specific parts of the present invention have been described in detail above, it is obvious to those skilled in the art that this specific technique is only a preferred embodiment, and the scope of the present invention is not limited thereby. something to do. Therefore, the substantial scope of the present invention will be defined by the appended claims and their equivalents.

Claims (16)

A polyimide precursor obtained by polymerizing a polymerization component comprising at least one diamine and at least one acid dianhydride,
A polyimide precursor in which the diamine among the polymerization components includes a diamine represented by the following Chemical Formula 1:
[Formula 1]

In Chemical Formula 1,
R ₁ and R ₂ are each independently an alkyl group having 1 to 3 carbon atoms, a haloalkyl group having 1 to 3 carbon atoms, or a halogen atom,
n and m are each independently an integer of 1 to 4. According to claim 1,
The polyimide precursors wherein R ₁ and R ₂ are each independently a fluoroalkyl group having 1 to 3 carbon atoms. According to claim 1,
The polyimide precursor wherein the polymerization component includes a diamine or an acid dianhydride having the structure of Formula 2 below:
[Formula 2]

In Chemical Formula 2,
R ₃ . Each of R ₄ is independently a monovalent organic group having 1 to 20 carbon atoms, and h is an integer of 3 to 200. According to claim 3,
The polyimide precursor of the compound of Formula 2 is included in 5 to 50% by weight based on the total weight of the polymerization component. According to claim 3,
The polyimide precursor of Formula 2 is a diamine comprising the structure of Formula 2-1:
[Formula 2-1]

In Chemical Formula 2-1,
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, when p + q = 100, p is 70 to 90, and q is 10 to 30. Applying a polyimide precursor composition comprising the polyimide precursor of claim 1 on a carrier substrate; And
A polyimide film prepared by a method comprising heating and curing the polyimide precursor composition. The method of claim 6,
A polyimide film having a residual stress of 40 MPa or less immediately after curing of the polyimide precursor composition. The method of claim 6,
After leaving the polyimide film at 25 ° C and 50% humidity for 3 hours, the polyimide film having a residual stress change value of 5 MPa or less. The method of claim 6,
The polyimide film having a yellowness of 15 or less of the polyimide film. A flexible device comprising the polyimide film of claim 6 as a substrate. Applying the polyimide precursor composition of claim 1 on a carrier substrate;
Heating the polyimide precursor composition to imidize polyamic acid to form a polyimide film;
Forming a device on the polyimide film; And
And peeling the polyimide film on which the element is formed from the carrier substrate. The method of claim 11,
The manufacturing process of a flexible device, wherein the manufacturing process includes an LTPS (low temperature polysilicon) process, an ITO process, or an oxide process. Diamine compound having the structure of formula (1):
[Formula 1]

In Chemical Formula 1,
R ₁ and R ₂ are each independently an alkyl group having 1 to 3 carbon atoms, a haloalkyl group having 1 to 3 carbon atoms, or a halogen atom,
n and m are each independently an integer of 1 to 4. The method of claim 13,
R ₁ and R ₂ are each independently a diamine compound having 1 to 3 carbon atoms. The method of claim 14,
¹ HNMR of the diamine compound is δ5.5 ~ 5.9 (s, 4H), δ6.8 ~ 6.4 (d, 2H), δ6.97 ~ 7.0 (s, 2H), δ7.04 ~ 7.1 (d, 2H) , δ 7.4 to 7.52 (d, 4H), δ 7.99 to 8.01 (d, 4H) showing a peak diamine compound. A method of preparing a diamine compound of Formula 1-1 by reacting a compound of Formula A below with a compound of Formula B below.

In the above formula,
R is an alkyl group having 1 to 3 carbon atoms, a haloalkyl group having 1 to 3 carbon atoms, or a halogen atom.

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