KR20200050135A - Polyimide precursor composition and polyimide film manufactured by using same - Google Patents

Abstract

The present invention adds a monomolecular compound containing an imide structure similar to a repeating unit structure of a polyimide polymer to a polyimide film as an organic filler, and thus can improve the ordering and orientation of the polyimide film to improve a refractive index of the film, thereby reducing the difference in refractive index with an upper layer to improve light emission efficiency.

Description

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

The present invention relates to a polyimide precursor composition and a polyimide film prepared therefrom, and more particularly, to a polyimide film having an improved refractive index.

The display device market is rapidly changing with a focus on flat panel displays (FPDs), which are easy to have a large area and can be thin and light. The flat panel display includes a liquid crystal display (LCD), an organic light emitting display (OLED), or an electrophoretic display (EPD).

In particular, in recent years, in order to further expand the application and use of such a flat panel display, attention has been focused on a so-called flexible display device in which a flexible substrate is applied to the flat panel display. The application of the flexible display device is mainly being studied mainly on mobile devices such as smart phones, and its application fields are gradually expanding.

In general, in manufacturing flexible display devices and lighting devices, TFT devices are manufactured by depositing a multilayer inorganic film such as a buffer layer, an active layer, and a gate insulator on a cured polyimide.

However, when light is emitted to the polyimide layer (substrate layer), the emission efficiency according to the difference between the refractive index of the multilayer upper layer made of the inorganic film and the refractive index of the polyimide layer may be reduced as described above.

The problem to be solved by the present invention is to provide a polyimide precursor composition comprising an organic single molecule capable of improving the refractive index.

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

Another problem to be solved by the present invention is to provide a polyimide film comprising an organic single molecule compound for improving refractive index.

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

In order to solve the problems of the present invention,

It provides a polyimide precursor composition comprising at least one monomolecular compound selected from the following formulas 1 and 2 or an imide thereof as an organic filler.

[Formula 1]

[Formula 2]

In Chemical Formulas 1 and 2,

X, Y and A are each independently substituted or unsubstituted arylene group having 5 to 24 carbon atoms, heterocycle having 5 to 24 carbon atoms, or two or more aromatic rings fused to each other to form a condensed ring or a single bond, O, S, SS, C (= O), -C (= O) O-, CH (OH), S (= O) ₂ , Si (CH ₃ ) ₂ , CR'R ", C (= O) NH and combinations thereof are monovalent, divalent, or tetravalent organic groups bound by a functional group selected from the group consisting of R, and R "are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, and a carbon number 1 It is selected from the group consisting of 10 to fluoroalkyl groups.

According to an embodiment, X, Y and A may be independently monovalent, divalent, or tetravalent organic groups each independently including a structure selected from Formulas 3a to 3g.

[Formula 3a]

[Formula 3b]

[Formula 3c]

[Formula 3d]

[Formula 3e]

[Formula 3f]

[Formula 3g]

In the formula 3a to 3g,

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

R ₁ to R ₈ are each independently a halogen atom selected from the group consisting of -F, -Cl, -Br and -I, hydroxyl group (-OH), thiol group (-SH), nitro group (-NO2) , 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, a substituent selected from an aryl group having 6 to 20 carbon atoms,

a is an integer from 0 to 4, b is an integer from 0 to 6, c is an integer from 0 to 8, d and e are each independently an integer from 0 to 4, f is an integer from 0 to 2, and g is 0 to 2 The integer, h is an integer from 0 to 2.

According to an embodiment, the X, Y and A may each independently be a monovalent, divalent, or tetravalent organic group including a structure selected from 4a to 4l below.

According to one embodiment, the monomolecular compound may be included in an amount of 0.1 to 50% by weight based on the total amount of the polyimide precursor composition.

 According to one embodiment, the polyimide precursor composition may include one or more monomolecular compounds selected from the following Chemical Formulas 1-1 and 2-1, which are imides of the Chemical Formulas 1 and 2 compounds.

[Formula 1-1]

[Formula 2-1]

In Chemical Formulas 1-1 and 2-1,

X, Y and A are as defined in Formulas 1 and 2 above.

According to one embodiment, the compound of Formula 1 or 2 may have a structure of Formula 11 or 12 below.

[Formula 11]

[Formula 12]

In Formulas 11 and 12, the definitions of X and Y are as defined in Formulas 1 and 2.

According to one embodiment, the compound of Formula 1-1 or 2-1 may have a structure of Formula 11-1 or 12-1.

[Formula 11-1]

[Formula 12-1]

In Formulas 11-1 and 12-1, the definitions of X and Y are as defined in Formulas 1 and 2.

In order to solve another problem of the present invention, there is provided a polyimide film prepared from the polyimide precursor composition.

According to one embodiment, the in-plane refractive index (n _TE ) value of the polyimide film may be improved by 0.001 to 0.1 compared to a polyimide film not containing the single molecule compound.

According to one embodiment, the YI of the polyimide film is 10 or less, and an average transmittance in a 380 to 780 nm section may be 60% or more.

According to one embodiment, the polyimide film may include one or more monomolecular compounds selected from the following Chemical Formulas 1-1 and 2-1.

[Formula 1-1]

[Formula 2-1]

In Chemical Formulas 1-1 and 2-1,

X, Y and A are each independently substituted or unsubstituted arylene group having 5 to 24 carbon atoms, heterocycle having 5 to 24 carbon atoms, or two or more aromatic rings fused to each other to form a condensed ring or single bond O , S, SS, C (= O), -C (= O) O-, CH (OH), S (= O) ₂ , Si (CH ₃ ) ₂ , CR'R ", C (= O) NH And a monovalent, divalent, or tetravalent organic group bonded by a functional group selected from the group consisting of a combination of R, and R "each independently being a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, and 1 to 1 carbon number. It is selected from the group consisting of 10 fluoroalkyl groups.

In addition, the present invention provides a flexible device comprising the polyimide film as a substrate.

According to the present invention, by adding a monomolecular compound having an imide structure similar to the repeating unit structure of a polyimide polymer to a polyimide film as an organic filler, the ordering and orientation of the polyimide film can be improved to improve the refractive index of the film. As a result, the difference in refractive index with the upper layer can be reduced to improve the light emission efficiency.

Figure 1 shows the structural change of the polyimide before and after the curing process of the polyimide precursor composition containing no single molecule compound.
Figure 2 shows the structural change of the polyimide before and after the curing process of the polyimide precursor composition containing a single molecule compound.

The present invention can be applied to various transformations and may 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 detailed descriptions of related well-known technologies may obscure the subject matter of the present invention, detailed descriptions thereof 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.

A flexible display comprising a polyimide as a substrate layer forms a TFT device by forming a film formed of a multilayer inorganic film such as a buffer layer, an active layer, and a gate insulator on a cured polyimide in manufacturing devices and lighting devices.

At this time, in general, in the case of a high transmittance polyimide film, the refractive index is n = 1.65 or less. When light is emitted to the polyimide layer, the difference between the refractive index (n = 1.8 or more) of the upper layer including the inorganic film and the refractive index of the polyimide layer By this, the emission efficiency can be reduced.

Therefore, in order to increase the efficiency of light emission from the flexible display element to the substrate layer, it is necessary to reduce the difference in refractive index between each layer configured to reduce the amount of light extinguished therein.

In order to solve the conventional problems as described above, the present invention,

It provides a polyimide precursor composition comprising at least one monomolecular compound selected from the following formulas 1 and 2 or an imide thereof as an organic filler.

[Formula 1]

[Formula 2]

In Chemical Formulas 1 and 2,

X, Y and A are each independently substituted or unsubstituted arylene group having 5 to 24 carbon atoms, heterocycle having 5 to 24 carbon atoms, or two or more aromatic rings fused to each other to form a condensed ring or a single bond, O, S, SS, C (= O), -C (= O) O-, CH (OH), S (= O) ₂ , Si (CH ₃ ) ₂ , CR'R ", C (= O) NH and combinations thereof are monovalent, divalent, or tetravalent organic groups bound by a functional group selected from the group consisting of R, and R "are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, and a carbon number 1 It is selected from the group consisting of 10 to fluoroalkyl groups.

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

The present invention, by using a single-molecular compound of the formula 1 to 2 having an imide group as an organic filler for controlling the refractive index of the polyimide film, while maintaining the other physical properties such as mechanical, optical, polyimide polyimide film The refractive index of can be improved.

For example, by adding the monomolecular compound to a polyimide precursor, ordering and orientation between molecules compared to a conventional polyimide alone curing progress sample is induced by inducing crystallization of the polyimide when the polymoleide is formed by a curing process. By improving, the refractive index can be improved and controlled. That is, by introducing the monomolecular compound as an organic filler (organic monomolecular) of the polyimide film, it is possible to improve the thickness of the polymer (PAA, PI) and density in the plane direction during high temperature curing, and improve the refractive index. Can be.

Each of X, Y and A may be a monovalent, divalent or tetravalent organic group each independently including a structure selected from Formulas 3a to 3g.

[Formula 3a]

[Formula 3b]

[Formula 3c]

[Formula 3d]

[Formula 3e]

[Formula 3f]

[Formula 3g]

In the formula 3a to 3g,

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

R1 to R8 are each independently a halogen atom selected from the group consisting of -F, -Cl, -Br and -I, a hydroxyl group (-OH), a thiol group (-SH), a nitro group (-NO ₂ ), A 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, a substituent group having an aryl group having 6 to 20 carbon atoms,

a is an integer from 0 to 4, b is an integer from 0 to 6, c is an integer from 0 to 8, d and e are each independently an integer from 0 to 4, f is an integer from 0 to 2, and g is 0 to 2 The integer, h is an integer from 0 to 2.

According to one embodiment, X, Y and A may each independently be a monovalent, divalent or tetravalent organic group comprising a structure selected from 4a to 4l below.

The monomolecular compound may be included in an amount of 0.1 to 50% by weight relative to the total amount of the polyimide precursor composition, preferably 0.1 to 10% by weight, and more preferably 0.5 to 5% by weight.

The monomolecular compounds of Chemical Formulas 1 and 2 may be synthesized by the following Reaction Schemes 1 to 2, respectively.

[Scheme 1]

[Scheme 2]

The monomolecular compounds of Chemical Formulas 1 to 2 may form compounds of Chemical Formulas 1-1 and 2-1 by imidization.

[Formula 1-1]

[Formula 2-1]

In Chemical Formulas 1-1 and 2-1, X, Y and A are the same as defined in Chemical Formulas 1 and 2.

According to one embodiment, the compound of Formula 1 or Formula 2 may have a structure of Formula 11 or 12 below.

[Formula 11]

[Formula 12]

In Formulas 11 and 12, the definitions of X and Y are as defined in Formulas 1 and 2.

In addition, the compound of Formula 1-1 or 2-1 may have a structure of Formula 11-1 or 12-1.

[Formula 11-1]

[Formula 12-1]

In Formulas 11-1 and 12-1, the definitions of X and Y are as defined in Formulas 1 and 2.

The polyimide precursor composition may include a monomolecular compound in the form of Formulas 1 to 2, or may be included in the imidized form of Formulas 1-1 to 2-1, or a mixture of the two forms. . Preferably, the monomolecular compound is capable of inducing the improvement of the interaction between the surrounding polyimide precursor molecules, that is, polyamic acid molecules and the monomolecular compound by imidization of the monomolecular compound during the curing process. In can be more efficient in obtaining the effect according to the invention.

The polyimide film prepared from the polyimide precursor composition according to the present invention can control the refractive index (n _TE ) in the plane direction and the refractive index (n _TM ) in the thickness direction by introducing an organic single molecule compound.

1 and 2 show a polyimide structure after a curing process depending on the presence or absence of a single molecule compound. In the case of the polyimide prepared by curing the polyimide precursor composition not containing the single molecule compound of FIG. 1, the polyimide particles are arranged in an inhomogeneous manner, but when introducing the single molecule compound according to the present invention as shown in FIG. By improving and inducing orientation and ordering between the polyimide molecules, the monomolecular compound can control (induce) the refractive index in the surface direction and the thickness direction, thereby increasing the surface direction refractive index.

The polyimide prepared from the polyimide precursor composition according to the present invention may have a refractive index of about 0.01 to 0.1 as compared to the polyimide without adding the organic filler containing the monomolecular compound, preferably 0.01 to 0.05 The refractive index can be improved.

According to one embodiment, the YI of the polyimide film according to the present invention may be 25 or less, preferably 10 or less, and an average transmittance in a 380 to 780 nm section may be 60% or more.

The polyimide precursor according to the present invention can be obtained by polymerizing at least one tetracarboxylic dianhydride and at least one diamine.

As the tetracarboxylic dianhydride, an intramolecular aromatic, alicyclic, or aliphatic tetravalent organic group, or a combination thereof, wherein the tetravalent organic groups of aliphatic, alicyclic, or aromatic are linked to each other through a crosslinked structure It may be a tetracarboxylic dianhydride containing an organic group. Preferably, a monocyclic or polycyclic aromatic, monocyclic or polycyclic alicyclic, or acid dianhydride having a structure in which two or more of them are connected by a single bond or a functional group may be used. Alternatively, the structure may be selected from a tetravalent organic group having a rigid structure, such as a heterocyclic ring structure in which a ring structure such as aromatic, alicyclic, or the like is fused, or a structure connected by a single bond. have.

For example, the tetracarboxylic dianhydride may include a tetravalent organic group having the structures of Formulas 5a to 5e:

[Formula 5a]

[Formula 5b]

[Formula 5c]

[Formula 5d]

[Formula 5e]

In Formulas 5a to 5e, R ₁₁ to R ₁₇ are each independently a halogen atom selected from the group consisting of -F, -Cl, -Br, and -I, hydroxyl group (-OH), 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, ,

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,

A ₁₁ and A ₁₂ are each independently a single bond, -O-, -CR ₁₈ R _19- , -C (= O)-, -C (= O) NH-, -S-, -SO _2- , phenyl It may be selected from the group consisting of a ren group and a combination 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. Can be.

Alternatively, the tetracarboxylic dianhydride may include a tetravalent organic group selected from the group consisting of the following Chemical Formulas 6a to 6n.

One or more hydrogen atoms in the tetravalent organic group of the formulas 6a to 6n are halogen atoms selected from the group consisting of -F, -Cl, -Br, and -I, hydroxyl group (-OH), thiol group (-SH), Substituted with a substituent selected from 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, and an aryl group having 6 to 20 carbon atoms. Can be. 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, ethyl, propyl, isopropyl, t-butyl, pentyl, and hexyl groups, and the aryl group is selected from phenyl, 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.

The diamine includes 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 structure in which two or more of these are connected by a single bond or a functional group It may be selected from the group consisting of divalent organic groups, or, aromatic, cycloaliphatic, or other ring structured compounds alone or fused (fused) heterocyclic ring structure, or rigid, such as a structure connected by a single bond (rigid ) May have a structure selected from divalent organic groups.

For example, it may be one containing a divalent organic group selected from the following formulas 7a to 7e.

[Formula 7a]

[Formula 7b]

[Formula 7c]

[Formula 7d]

[Formula 7e]

In the above formulas 7a to 7e,

R ₂₁ to R ₂₇ are each independently a halogen atom selected from -F, -Cl, -Br and -I, a hydroxyl group (-OH), a thiol group (-SH), a nitro group (-NO ₂ ), It may be selected from the group consisting of a cyano group, an alkyl group having 1 to 10 carbon atoms, a halogenoalkoxy having 1 to 4 carbon atoms, a halogenoalkyl having 1 to 10 carbon atoms, and an aryl group having 6 to 20 carbon atoms,

In addition, A21 and A22 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, a methyl group, Ethyl groups, propyl groups, isopropyl groups, n-butyl groups, tert-butyl groups, pentyl groups, etc.) and haloalkyl groups having 1 to 10 carbon atoms (for example, those selected from trifluoromethyl groups, etc.) , -C (= O)-, -C (= O) O-, -C (= O) NH-, -S-, -SO-, -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-, 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. ,

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 8a to 8p.

At least one hydrogen atom in the divalent organic group of the formulas 8a to 8p 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.

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. .

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.

For example, the organic solvent that can be used for the polymerization reaction of the diamine and the acid dianhydride may include a solvent having a positive partition coefficient (LogP value) at 25 ° C, and the organic solvent may have a boiling point of 300 ° C or less, 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 the ACD / LogP module of ACD / Percepta platform of ACD / Labs, and the ACD / LogP module uses a 2D structure of the molecule to implement an algorithm based on QSPR (Quantitative Structure-Property Relationship) methodology. To use.

The partition coefficient (Log P) positive solvent may be an amide-based solvent, and the amide-based solvent is dimethylpropionamide (DMPA), diethylpropionamide (DEPA), N, N-diethylacetamide (N, N-diethylacetamide, DEAc), N, N-diethylformamide (N, N-diethylformamide, DEF), N-ethylpyrrolidone (N-ethylpyrrolidone, NEP).

The method for reacting the tetracarboxylic dianhydride with diamine may 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 resulting 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 may be carried out at -20 to 80 ℃, preferably 0 to 80 ℃. When 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 fairness 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 obtaining a polyimide precursor as a solid powder, you may melt | dissolve this in an organic solvent and make it a solution. For example, in the polymerization reaction, an organic solvent having a positive LogP may be used, and an organic solvent having a negative LogP may be used as an organic solvent to be mixed later.

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 or less It is preferable to adjust to have a viscosity of. 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.

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

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

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

According to one embodiment, the polyimide film composition obtained as above,

Applying the polyimide film composition on a substrate; And

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

At this time, as the substrate, a glass, metal substrate, or plastic substrate may be used without particular limitation, and among them, excellent thermal and chemical stability during the imidization and curing process for the polyimide precursor, and curing without additional release agent treatment. A glass substrate that can be easily separated without damage to the formed polyimide-based film 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 over 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 10 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 performed according to a conventional method, and specifically, may be performed 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 is applied to a substrate, and heat-treated on an IR oven, a hot air oven, or a hot plate, wherein the heat treatment temperature may range from 280 to 450 ° C, preferably 290 to 400 ° C, and the It may be carried out in a multi-step heat treatment within the temperature range. The heat treatment process may be performed for 20 minutes to 70 minutes, and preferably 20 minutes to 60 minutes.

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

The polyimide film according to the present invention can increase the refractive index, and can be used as a substrate layer in a flexible display device, thereby reducing the difference in refractive index with each layer constituting the device, from which light disappearing from the inside By reducing the amount of, it is possible to effectively increase the light emission (bottom emission) efficiency.

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.

<Synthesis Example 1>

Single molecule compound A was synthesized by the method shown in Scheme 1-1.

Specifically, after filling 80 g of the organic solvent DEAc in a stirrer through which a nitrogen stream flows, 18.99 g (0.204 mol) of aniline was dissolved while maintaining the reactor temperature at 25 ° C. Compound A was synthesized by adding 30.0 g (0.102 mol) of s-BPDA (3,3 ', 4,4' '-Biphenyltetracarboxylic dianhydride) and 93.7 g of DEAc to the aniline solution at the same temperature and dissolving and stirring for a period of time.

[Scheme 1-1]

<Synthesis Example 2>

Single molecule compound B was synthesized by the method shown in Scheme 2-1.

Specifically, after filling 55.0 g of the organic solvent DEAc in a stirrer through which a nitrogen stream flows, 16.22 g (0.051 mol) of TFMB (2,2'-Bis (trifluoromethly) benzidine) was dissolved while maintaining the reactor temperature at 25 ° C. Compound B was synthesized by adding 15.0 g (0.102 mol) of PH (Phthalic anhydride) and 55.972 g of DEAc at the same temperature and dissolving and stirring for a period of time in the aniline solution.

[Scheme 2-1]

<Comparative Example 1>

After filling 110.0 g of DEAc in a stirrer through which a nitrogen stream flows, 21.4 g (0.067 mol) of TFMB (2,2'-Bis (trifluoromethyl) benzidine) is added at the same temperature and dissolved while maintaining the temperature of the reactor at 25 ° C. Ordered. Pyromellitic dianhydride (PMDA) 7.2 g (0.033 mol) and BPDA (3,3 ′, 4,4 ′ '-Biphenyltetracarboxylic dianhydride) 9.71 g (0.033 mol) were added to the TFMB added solution at the same temperature for 24 hours. The mixture was stirred to obtain a polyimide precursor composition.

<Example 1>

Compound A was added at 2.5% by weight to the polyimide precursor composition of Comparative Example 1.

<Example 2>

The compound B was added at 2.5% by weight to the polyimide precursor composition of Comparative Example 1.

<Experimental Example 1>

Each polyimide precursor composition prepared in Examples 1 to 2 and Comparative Example 1 was spin coated on a glass substrate. The glass substrate coated with the polyimide precursor composition was placed in an oven, heated at a rate of 5 ° C / min, and maintained at 80 ° C for 30 minutes and 300 ° C for 30 minutes to undergo a curing process to prepare a polyimide film.

Table 1 shows the physical properties of each film.

<Refractive index measurement>

The prepared polyimide film was peeled off, and a refractive index was measured at a wavelength of 540 nm using a prism coupler measurement equipment.

<Measurement of Yellowness (YI)>

Yellowness was measured using ASTM D1925 measurement conditions.

⊙: YI 10 or less

○: YI 25 or less

X: YI 25 or higher

<Measurement of transmittance>

The average transmittance in the 380nm to 780nm section was measured using a UV spectrophotometer.

⊙: 60% or more

○: 50% ~ 60%

X: 50% or less

YI Transmittance Refractive index (nTE) Comparative Example (PI only) ⊙ ⊙ 1.6447 Example 1 ⊙ ⊙ 1.6557 Example 2 ⊙ ⊙ 1.6608

As can be seen from the results of Table 1, the monomolecular compound according to the present invention can be added to the polyimide precursor composition, thereby improving the surface refractive index while maintaining the optical and physical properties of the polyimide itself.

From this, the substrate for a flexible display device comprising a polyimide film according to the present invention can reduce the difference in refractive index with an inorganic layer formed in the device, thereby reducing the amount of light that is extinguished therein. It is possible to effectively increase the efficiency of bottom emission.

Since the specific parts of the present invention have been described in detail above, it is obvious to those skilled in the art that such specific techniques are only preferred embodiments, 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 (12)

Polyimide precursor composition comprising at least one monomolecular compound selected from Formulas 1 and 2 or an imide thereof as an organic filler:
[Formula 1]

[Formula 2]

In Chemical Formulas 1 and 2,
X, Y and A are each independently substituted or unsubstituted arylene group having 5 to 24 carbon atoms, heterocycle having 5 to 24 carbon atoms, or two or more aromatic rings fused to each other to form a condensed ring or single bond O , S, SS, C (= O), -C (= O) O-, CH (OH), S (= O) ₂ , Si (CH ₃ ) ₂ , CR'R ", C (= O) NH And a monovalent, divalent, or tetravalent organic group bonded by a functional group selected from the group consisting of a combination of R, and R "each independently being a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, and 1 to 1 carbon number. It is selected from the group consisting of 10 fluoroalkyl groups. According to claim 1,
The polyimide precursor composition wherein X, Y and A are each independently a monovalent, divalent, or tetravalent organic group comprising a structure selected from Formulas 3a to 3g:
[Formula 3a]

[Formula 3b]

[Formula 3c]

[Formula 3d]

[Formula 3e]

[Formula 3f]

[Formula 3g]

In the formula 3a to 3g,
Q is a single bond, O, S, SS, C (= O), -C (= O) O-, CH (OH), S (= O) ₂ , Si (CH ₃ ) ₂ , -CR'R " -, C (= O) NH and a functional group selected from the group consisting of a combination thereof, wherein R 'and R "are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms and a fluoroalkyl group having 1 to 10 carbon atoms. Is selected from the group consisting of,
R ₁ to R ₈ are each independently a halogen atom selected from the group consisting of -F, -Cl, -Br and -I, hydroxyl group (-OH), thiol group (-SH), nitro group (-NO2) , 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, a substituent selected from an aryl group having 6 to 20 carbon atoms,
a is an integer from 0 to 4, b is an integer from 0 to 6, c is an integer from 0 to 8, d and e are each independently an integer from 0 to 4, f is an integer from 0 to 2, and g is 0 to 2 The integer, h is an integer from 0 to 2. According to claim 1,
The polyimide precursor composition wherein X, Y and A are each independently a monovalent, divalent or tetravalent organic group including a structure selected from 4a to 4l:

. According to claim 1,
A polyimide precursor composition comprising the single molecule compound in an amount of 0.1 to 50% by weight based on the total amount of the polyimide precursor composition. According to claim 1,
A polyimide precursor composition comprising at least one monomolecular compound selected from Formulas 1-1 and 2-1:
[Formula 1-1]

[Formula 2-1]

In Chemical Formulas 1-1 and 2-1,
X, Y and A are as defined for Formulas 1 and 2. According to claim 1,
The compound of Formula 1 or 2 is a polyimide precursor composition having the structure of Formula 11 or 12:
[Formula 11]

[Formula 12]

In Formulas 11 and 12, X and Y are as defined for Formulas 1 and 2. The method of claim 5,
The polyimide precursor composition wherein the compound of Formula 1-1 or 2-1 has the structure of Formula 11-1 or 12-1:
[Formula 11-1]

[Formula 12-1]

In Formulas 11-1 and 12-1, the definitions of X and Y are the same as those defined for Formulas 1 and 2. A polyimide film prepared from the polyimide precursor composition of claim 1. The method of claim 8,
A polyimide film having an in-plane refractive index (n _TE ) value of the polyimide film improved by 0.001 to 0.1 compared to a polyimide film not containing the single molecule compound. The method of claim 8,
The polyimide film having a YI of 10 or less and an average transmittance of 60% or more in a 380 to 780 nm section. The method of claim 8,
The polyimide film wherein the polyimide film includes at least one monomolecular compound selected from the following Chemical Formulas 1-1 and 2-1:
[Formula 1-1]

[Formula 2-1]

In Chemical Formulas 1-1 and 2-1,
X, Y and A are each independently substituted or unsubstituted arylene group having 5 to 24 carbon atoms, heterocycle having 5 to 24 carbon atoms, or two or more aromatic rings fused to each other to form a condensed ring or single bond O , S, SS, C (= O), -C (= O) O-, CH (OH), S (= O) ₂ , Si (CH ₃ ) ₂ , CR'R ", C (= O) NH And a monovalent, divalent, or tetravalent organic group bonded by a functional group selected from the group consisting of a combination of R, and R "each independently being a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, and 1 to 1 carbon number. It is selected from the group consisting of 10 fluoroalkyl groups. A flexible device comprising the polyimide film according to claim 8 as a substrate.

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