WO2018143583A2 - Polyimide and polyimide film, prepared therefrom, for flexible display - Google Patents

Abstract

Described is a polyimide prepared from a diamine containing a spiro or cardo group in a molecule structure, wherein the dimensional stability of the polyimide can be improved at a high temperature, and thus the polyimide can provide a polyimide film useful for a flexible substrate.

Description

Polyimide and Polyimide Film for Flexible Display Made Therefrom

This application claims the benefit of priority based on Korean Patent Application No. 10-2017-0013726, filed January 31, 2017 and 10-2017-0167165, filed December 7, 2017, The contents are included as part of this specification.

The present invention relates to a polyimide having improved heat resistance and thermal stability and a polyimide film for flexible display including the same.

Polyimide (PI) is a polymer with relatively low crystallinity or mostly amorphous structure. It is easy to synthesize, can make thin film, and does not need a crosslinker for curing. It is a polymer material that has excellent heat resistance, chemical resistance, excellent mechanical properties, electrical properties and dimensional stability. It is widely used in electric and electronic materials such as automotive, aerospace, flexible circuit boards, liquid crystal alignment films for LCDs, adhesives and coating agents. have.

However, although polyimide is a high-performance polymer material with high thermal stability, mechanical properties, chemical resistance, and electrical properties, it does not satisfy the colorless and transparent property, which is a basic requirement for the display field, and also requires a lower coefficient of thermal expansion. There is a problem. For example, Kapton's coefficient of thermal expansion, sold by DuPont, has a low coefficient of thermal expansion of about 30 ppm / ° C, but this also does not meet the requirements of plastic substrates. Therefore, many studies have been conducted to minimize optical characteristics and thermal hysteresis while maintaining basic characteristics of polyimide.

However, in order to use in the display field, there is a need for the development of a polymer for a flexible display having a lower coefficient of thermal expansion, high solubility, transparency and thermal stability.

An object of the present invention is to provide a polyimide with improved heat resistance and thermal stability.

Another object of the present invention is to provide a polyimide film containing the polyimide.

The present invention also provides a diamine with a novel structure comprising a spiro or cardo group in its molecular structure.

The present invention to solve the above technical problem,

It provides a polyimide prepared from a polymerization component comprising tetracarboxylic dianhydride and at least one diamine selected from the following formulas (1a) to (1e).

[Formula 1a]

[Formula 1b]

[Formula 1c]

[Formula 1d]

[Formula 1e]

In Chemical Formulas 1b to 1e,

R ₁ and R ₂ are each independently a hydrogen atom, a halogen atom, 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, and a carbon number It is a substituent selected from the halogenoalkoxy of 1-4, the halogenoalkyl of 1-10, C6-C20, and the aryl group,

According to an embodiment, the diamine of Formula 1 may be included in an amount of 30 to 100 mol% with respect to the total content of the diamine.

According to one embodiment, the coefficient of thermal expansion (CTE) of the polyimide may be 50ppm / ℃ or less.

According to one embodiment, the glass transition temperature (Tg) of the polyimide may be 330 ℃ or more.

In order to solve the another subject of this invention, the polyimide film for flexible displays containing the said polyimide is provided.

The present invention also provides a diamine represented by any one of the following Formulas 1a to 1e.

[Formula 1a]

[Formula 1b]

[Formula 1c]

[Formula 1d]

[Formula 1e]

In Chemical Formulas 1a to 1e,

Wherein R _1, R ₂ each independently represent a hydrogen atom, -F, -Cl, -Br, and a halogen atom, is selected from -I hydroxyl group (-OH), thiol (-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, and an aryl group having 6 to 20 carbon atoms.

The polyimide according to the present invention may be prepared from diamines containing spiro or cardo groups in which two or more phenyl groups are linked and fixed, thereby improving dimensional stability against heat as well as high glass transition temperature. . The polyimide film made of the polyimide according to the present invention has excellent thermal stability, and is a flexible device with high temperature process, in particular OLED (organic light) using an oxide TFT (thin film transistor) and LTPS (low temperature polysilicon) process. emitting diode) device.

As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all transformations, equivalents, and substitutes included in the spirit and scope of the present invention. In the following description of the present invention, if it is determined that the detailed description of the related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

All compounds or organic groups herein may be substituted or unsubstituted unless otherwise specified. Herein, the term "substituted" means that at least one hydrogen contained in the compound or the 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, and a hydroxy group And substituted with a substituent selected from the group consisting of alkoxy groups, carboxylic acid groups, aldehyde groups, epoxy groups, cyano groups, nitro groups, amino groups, sulfonic acid groups and derivatives thereof having 1 to 10 carbon atoms.

In addition, in the present specification, 'combination thereof' unless otherwise specified, a single bond, a double bond, a triple bond, an alkylene group having 1 to 10 carbon atoms (for example, methylene group (-CH _2- ), an ethylene group (-CH ₂ CH ₂ -), etc.), (a methylene group in, for example, fluoro (-CF ₂ -) alkylene fluoroalkyl group having 1 to 10 carbon atoms, ethylene perfluoro (-CF ₂ CF ₂ Etc.), a hetero atom such as N, O, P, S, or Si or a functional group containing the same (e.g., an intramolecular carbonyl group (-C (= 0)-), ether group (-O-), It is bound by a linking group such as ester group (-COO-), -S-, -NH- or -N = N-, etc.) or two or more functional groups are condensed, connected do.

 Flexible devices with high temperature processes require heat resistance at high temperatures, especially for organic light emitting diode (OLED) devices using oxide thin film transistor (TFT) and low temperature polysilicon (LTPS) processes. The above is also close to 500 degreeC.

At such a temperature, even polyimide having excellent heat resistance is likely to be pyrolyzed, and thermal shrinkage or expansion may occur. Therefore, in order to manufacture a flexible device, it is necessary to develop a polyimide that can exhibit excellent thermal stability while maintaining high transparency at high temperature with excellent mechanical properties.

The present invention provides an ultrahigh temperature resistant polyimide made from diamines having a novel structure.

Another object of the present invention to provide a polyimide film containing the polyimide.

 The present invention provides a diamine represented by one selected from the following Chemical Formulas 1a to 1e.

[Formula 1a]

[Formula 1b]

[Formula 1c]

[Formula 1d]

[Formula 1e]

In Chemical Formulas 1b to 1e,

R ₁ and R ₂ are each independently a hydrogen atom, a halogen atom, 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, and a carbon number It is a substituent chosen from the halogeno alkoxy of 1-4, the halogenoalkyl of 1-10 carbon atoms, and the aryl group of 6-20 carbon atoms.

In addition, the present invention,

In the polyimide manufactured from a polymerization component containing tetracarboxylic dianhydride and at least one diamine,

It provides a polyimide wherein the diamine is a diamine of any one of Formulas 1a to 1e.

According to one embodiment, the diamine of the general formula (1) may be included in the content of 30 to 100 mol% with respect to the total content of the diamine in the polymerization component, preferably it may be included in a content of 50 to 100 mol%.

The diamine according to the present invention has a structure including a spiro group or a cardo group in which two or more phenyl groups are connected and fixed, and a polyimide comprising a group in which a phenyl group is not fixed. In this case, although the glass transition temperature is increased, but the CTE (thermal expansion coefficient) is increased, the thermal stability may be lowered. However, in the present invention, a polyimide having a high thermal transition and a decrease in the CTE is reduced by fixing a phenyl group, thereby obtaining a polyimide having excellent thermal stability. Can provide.

According to one embodiment, the glass transition temperature of the polyimide may be 330 ℃ or more, preferably 350 ℃ or more.

According to an embodiment, the CTE of the polyimide may be 50 ppm / ° C. or less, preferably 30 ppm / ° C. or less, for example, 10 to 30 ppm / ° C.

At this time, the CTE is set to be pulled with a force of 0.02N after a sample of a thickness of 10μm, width 5mm, length 5cm to the jig so that the measurement length is 16mm, and the temperature increase rate to 5 ℃ / min to rise to 300 ℃ ( After the first temperature rise) and then cooled to 50 ° C (primary cooling), and the temperature is increased to 450 ° C (secondary temperature increase) in the step of measuring the value in the 100 ~ 250 ℃ section.

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

The tetracarboxylic dianhydride may be used as long as it is generally used for the production of polyimide. For example, tetracarboxylic dianhydrides usable in the production of polyimides are tetravalent organic groups of aromatic, cycloaliphatic, or aliphatic in the molecule, or combinations thereof, and aliphatic, cycloaliphatic, or aromatic tetravalent organic groups. It may be tetracarboxylic dianhydride including tetravalent organic groups connected to each other via a crosslinked structure. For example, it may be a tetracarboxylic dianhydride including a tetravalent organic group structure selected from the group consisting of tetravalent organic groups of Formulas 2a to 2e and combinations thereof.

[Formula 2a]

[Formula 2b]

[Formula 2c]

[Formula 2d]

[Formula 2e]

In Formulas 2a to 2e, R ₁₁ to R ₁₇ each independently represent a hydrogen atom, a halogen atom (selected from -F, -Cl, -Br, and -I), a hydroxyl group (-OH), and a thiol group (-SH ), A nitro group (-NO ₂ ), a cyano group, an alkyl group having 1 to 10 carbon atoms, a halogenoalkoxy having 1 to 4 carbon atoms, a halogenoalkyl having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms Can,

A1 is an integer of 0 to 2, a2 is an integer of 0 to 4, a3 is an integer of 0 to 8,

a4 and a5 may each independently represent an integer of 0 to 3, a6 and a9 may each independently represent an integer of 0 to 3, and a7 and a8 may each independently represent an integer of 0 to 9, and

A ₁₁ and A ₁₂ are each independently a single bond, -O-, -CR ₁₈ R _19- , -C (= 0)-, -C (= 0) NH-, -S-, -SO _2- , It may be selected from the group consisting of a phenylene group 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 Can be.

For example, tetracarboxylic dianhydride used in the present invention may be used in the structure, but tetracarboxylic dianhydride including a tetravalent organic group selected from the group consisting of 3a to 3r, but is not limited thereto.

In 3l, A ₂ is a single bond, -O-, -C (= 0)-, -C (= 0) NH-, -S-, -SO _2- , a phenylene group and a combination thereof May be selected, v is an integer of 0 or 1, and in 3r x is an integer of 1 to 10.

Further, at least one hydrogen atom present in the tetravalent organic group of 3a to 3r may be selected from the group consisting of -F, -Cl, -Br and -I, a halogen atom, 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, an aryl group having 6 to 20 carbon atoms It may be substituted with a substituent.

In the present invention, other types of diamines may be used in addition to the diamine of Chemical Formula 1, and the diamine may be used as long as it is generally used for preparing polyimide, and specifically, an aliphatic, alicyclic or aromatic divalent compound. As an organic group or a combination group thereof, an aliphatic, alicyclic or aromatic divalent organic group may be directly connected or a divalent organic group connected to each other through a crosslinking structure, for example, 2 of Formulas 4a to 4g It may be a diamine containing a divalent organic group structure selected from the group consisting of a divalent organic group and a combination thereof.

[Formula 4a]

[Formula 4b]

[Formula 4c]

[Formula 4d]

[Formula 4e]

In Chemical Formulas 4a to 4e

R ₂₁ to R ₂₈ each independently represent 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.), halogen group and hydroxy group Carboxyl groups, alkoxy groups having 1 to 10 carbon atoms (e.g., methoxy groups, ethoxy groups, propoxy groups, tert-butoxy groups, etc.), and fluoroalkyl groups having 1 to 10 carbon atoms (e.g., trifluoromethyl groups, etc.) ) Can be selected from the group consisting of

In addition, A ₂₁ and A ₂₂ are each independently a single bond, -O-, -CR'R "-(wherein R 'and R" are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms (e.g., Methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, tert-butyl group, pentyl group, etc.) and a C1-C10 haloalkyl group (for example, trifluoromethyl group 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-, a monocyclic or polycyclic cycloalkylene group having 6 to 18 carbon atoms (e.g. For example, a cyclohexylene group, etc.), a monocyclic or polycyclic arylene group having 6 to 18 carbon atoms (e.g., a phenylene group, a naphthalene group, a fluorenylene group, etc.), and combinations thereof may be selected. Can,

b ₁ , b ₄ and b ₅ are each independently an integer from 0 to 4, b ₂ is an integer from 0 to 6, b ₃ is an integer from 0 to 3, b ₆ and b ₉ are each independently 0 or is an integer of 1, b _7, and ₈ b are each independently an integer of 0 to 10.

For example, the diamine used in the present invention may further be a diamine including a divalent organic group selected from the group consisting of the formulas 5a to 5t in the structure, but is not limited thereto.

The at least one hydrogen atom present in the divalent organic group of 5a to 5t is a halogen atom selected from -F, -Cl, -Br and -I, hydroxyl group (-OH), thiol group (-SH), nitro Or a substituent selected from 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, and an aryl group having 6 to 20 carbon atoms. have.

According to one embodiment,

The polymerization component may further include a diamine of the following Chemical Formula 6 together with the diamine selected from Chemical Formulas 1a to 1e.

[Formula 6]

In Chemical Formula 6,

R ₃₁ and R ₃₂ 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 ), A substituent selected from a cyano group, an alkyl group having 1 to 10 carbon atoms, a halogenoalkoxy having 1 to 4 carbon atoms, a halogenoalkyl having 1 to 10 carbon atoms, and an aryl group having 6 to 20 carbon atoms,

n and m are each independently an integer of 0-4.

Q ₁ is a single bond, -O-, -CR ₁₈ R _19- , -C (= O)-, -C (= O) O-, -C (= O) NH-, -S-, -SO ₂ -A phenylene group 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 Will be.

The method for reacting the tetracarboxylic dianhydride with the diamine can be carried out according to a conventional polyimide precursor polymerization production method such as solution polymerization. Specifically, after dissolving diamine in an organic solvent, tetracarboxylic dianhydride is added to the resulting mixed solution and polymerized to produce a polyamic acid as a polyimide precursor.

The reaction can be carried out under an inert gas or nitrogen stream and can be carried out in anhydrous conditions.

In addition, the polymerization temperature may be carried out at -20 to 60 ℃, preferably 0 to 45 ℃. If the reaction temperature is too high, the reactivity may be increased to increase the molecular weight, it may be disadvantageous in terms of the process by increasing the viscosity of the precursor composition.

As the organic solvent that can be used in the polymerization reaction, specifically, γ-butyrolactone, 1,3-dimethyl-imidazolidinone, methyl ethyl ketone, cyclohexanone, cyclopentanone, 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 (cellosolve) such as dipropylene glycol diethyl ether and triethylene glycol monoethyl ether; Ethyl acetate, butyl acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, dipropylene glycol monomethyl ether acetate, ethanol, propanol, ethylene glycol, propylene glycol, carbitol, dimethyl Acetamide (DMAc), N, N-diethylacetamide, dimethylformamide (DMF), diethylformamide (DEF), N-methylpyrrolidone (NMP), N-ethylpyrrolidone (NEP), 1,3-dimethyl-2-imidazolidinone, N, N-dimethylmethoxyacetamide, dimethyl sulfoxide, pyridine, dimethyl sulfone, hexamethylphosphoramide, tetramethylurea, N-methylcaprolactam, tetrahydro Furan, m-dioxane, P-dioxane, 1,2-dimethoxyethane, bis (2-methoxyethyl) ether, 1,2-bis (2-methoxyethoxy) ethane, bis [2- ( 2-methoxyethoxy)] ether and mixtures thereof To choose books that can be used.

Preferably, sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide, formamide solvents such as N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, Acetamide solvents such as N, N-diethylacetamide, pyrrolidone solvents such as N-methyl-2-pyrrolidone and N-vinyl-2-pyrrolidone, phenol, o-, m- or p Phenol solvents such as cresol, xylenol, halogenated phenol, catechol, or hexamethylphosphoramide, γ-butyrolactone, and the like, and these may be used alone or as a mixture, more preferably N, N-diethylacetamide (N, N-diethylacetamide, DEAc), N, N-diethylformamide (DEF), N-ethylpyrrolidone (NEP) or their It may be selected from the mixture.

According to one embodiment, the organic solvent may further use an aromatic hydrocarbon such as xylene, toluene, and also up to about 50% by weight of alkali metal salt or alkaline earth in the solvent to promote dissolution of the polymer. Further metal salts may be added.

 It is preferable that the polyimide precursor solution manufactured by the above-mentioned manufacturing method contains solid content in the quantity which makes the said composition have appropriate viscosity in consideration of processability, such as applicability | paintability in the film formation process. According to one embodiment, the content of the composition may be adjusted such that the total polyimide precursor is 5 to 20% by weight, preferably 8 to 18% by weight, more preferably 8 to 12% by weight. have.

Alternatively, the polyimide precursor solution may be adjusted to have a viscosity of 2,000 cP or more, or 3,000 cP or more, and the viscosity of the polyimide precursor solution may be 10,000 cP or less, preferably 9,000 cP or less, and more preferably 8,000 cP. It is preferable to adjust so that it may have the following viscosity. When the viscosity of the polyimide precursor solution exceeds 10,000 cP, the efficiency of degassing during the processing of the polyimide film is lowered. As a result, not only the efficiency of the process but also the resulting film has poor surface roughness due to foaming, resulting in electrical, optical and mechanical properties. Can be degraded.

Further, 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. It is preferable that molecular weight distribution (Mw / Mn) is 1.1-2.5. If the weight average molecular weight or molecular weight distribution of the polyimide is out of the above range, it may be difficult to form a film or the characteristics of the polyimide film such as permeability, heat resistance and mechanical properties may be deteriorated.

Subsequently, the polyimide precursor obtained as a result of the polymerization reaction is imidated, whereby a transparent polyimide film can be produced. In this case, the imidization process may specifically include a chemical imidization method or a thermal imidization method.

For example, a dehydrating agent and an imidization catalyst are added to the polymerized polyimide precursor solution, and then heated to a temperature of 50 to 100 ° C. to imidize by chemical reaction, or the alcohol is removed while refluxing the solution. Polyimide can be obtained by the method of drawing.

In the chemical imidization method, pyridine, triethylamine, picoline, or quinoline may be used as the imidization catalyst, and in addition, N- of substituted or unsubstituted nitrogen-containing heterocyclic compounds and nitrogen-containing heterocyclic compounds Oxide compounds, substituted or unsubstituted amino acid compounds, aromatic hydrocarbon compounds having a hydroxyl group or aromatic heterocyclic compounds, and especially 1,2-dimethylimidazole, N-methylimidazole, N-benzyl-2- Lower alkylimidazoles such as methylimidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, 5-methylbenzimidazole, isoquinoline, 3,5-dimethylpyridine, 3,4 Substituted pyridines such as -dimethylpyridine, 2,5-dimethylpyridine, 2,4-dimethylpyridine, 4-n-propylpyridine, p-toluenesulfonic acid and the like may also be used.

As the dehydrating agent, acid anhydrides such as acetic anhydride can be used.

Alternatively, the polyimide precursor solution may be imidized by applying a heat treatment on a substrate.

The polyimide precursor solution may be in the form of a solution dissolved in an organic solvent, and in the case of having such a form, for example, when a polyimide precursor is synthesized in an organic solvent, the solution may be the reaction solution itself obtained. The reaction solution may be diluted with another solvent. Moreover, when a polyimide precursor is obtained as a solid powder, it may be made to melt | dissolve this in the organic solvent and set it as the solution.

The present invention comprises the steps of applying the polyimide precursor solution on a substrate;

It provides a method for producing a polyimide film comprising the step of heat-treating the applied polyimide precursor solution.

The polyimide precursor solution 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 be in the range of 300 to 500 ° C, preferably 320 to 480 ° C, and the temperature range It can also be carried out in a multistage heating process. The heat treatment process may be carried out for 20 to 70 minutes, preferably for 20 to 60 minutes.

The organic solvent contained in the polyimide precursor solution of the present invention may be the same as the organic solvent used in the synthesis reaction.

As long as this invention is a range which does not impair an effect, you may add an imidation promoter etc. for the purpose of advancing a silane coupling agent, a crosslinkable compound, and imidation efficiently.

In addition, the polyimide-based film has a haze value of 1 or less, preferably 0.9 or less, or 0.7 or less, and more preferably 0.5 or less, thereby providing a polyimide film having improved transparency. At this time, the thickness of the polyimide film may be 8 to 15㎛, preferably 10 to 12㎛.

 In addition, the transmittance of light with a wavelength of 380 to 760 nm in the film thickness range of 5 to 30 μm is 80% or more, and the yellowness (YI) is about 25 or less, preferably about 20 or less, and more preferably about 16 or less. Or a colorless transparent polyimide film having a value of 15 or less. By having excellent light transmittance and yellowness as described above it can exhibit a markedly improved transparency and optical properties.

In addition, the polyimide film has an in-plane retardation value R _in of about 0 to 100 nm, and an absolute value of the retardation value R _{th in the} thickness direction is about 1500 nm or less, or 0 to 1000 nm or less, preferably 30 to 800 nm. Or less, more preferably, 50 to 700 nm or less. Visibility suitable for a display may be expressed in the phase difference range in the thickness direction, and when the thickness direction phase difference is 1500 nm or more, a phase difference occurs in the polyimide film so that light is distorted and thus visibility may be significantly reduced.

In still another embodiment of the present invention, an article including the polyimide copolymer is provided.

The molded article may be a film, a fiber, a coating material, an adhesive material, but is not limited thereto. The molded article may be formed by a dry wet method, a dry method, a wet method, etc. using the composite composition of the copolymer and the inorganic particles, but is not limited thereto. Specifically, as described above, the molded article may be an optical film, in which case, the composition comprising the polyimide copolymer is applied to the substrate by a method such as spin coating, and then easily dried and cured. Can be prepared.

The polyimide according to the present invention may exhibit excellent heat resistance against thermal changes that may occur in a high temperature process, such as an element substrate, a display cover substrate, an optical film, an integrated circuit (IC) package, and an adhesive film. (adhesive film), multilayer FPC (flexible printed circuit), tape, a touch panel, a protective film for an optical disk, etc. can be used in various fields.

According to another embodiment of the present invention provides a display device including the molded article. Specifically, the display device may include a liquid crystal display device (LCD), an organic light emitting diode (OLED), and the like, and in particular, a low temperature polysilicon (LTPS) process requiring a high temperature process It may be suitable for an OLED device using, but is not limited thereto.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily practice the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

Synthesis Example 1

Diamine compound of formula 10 (Compound 10) was prepared as follows.

Compound A (20.0g, 42.4mmol) and Compound B (15.7g, 84.8mmol) were dispersed in dimethylformaldehyde (200ml), and copper iodide (1.6g, 8.5mmol) was added and stirred for 12 hours. After the reaction was completed, the temperature was lowered to room temperature, and the solid obtained by filtration was extracted with chloroform and concentrated to prepare an intermediate material. This intermediate material was completely dissolved in tetrahydrofuran (100 ml), and then, an aqueous hydrazine solution (10 ml) was added thereto, followed by heating and stirring for 1 hour. After the reaction was completed, the mixture was cooled to room temperature and filtered, and the filtrate was added to water (250 mL) to form a precipitate. Filtration gave a compound of Chemical Formula 10 (7.2 g, 49% yield). MS [M + H] ⁺ = 347

 [Formula 10]

Synthesis Example 2

The diamine compound of formula 11 (Compound 11) was prepared as follows.

Compound A (30.0 g, 63.6 mmol) and Compound C (30.7 g, 127.2 mmol) were dissolved completely in tetrahydrofuran (300 ml), and then 1.5 M potassium carbonate solution (150 ml) was added thereto, and tetrakistriphenyl-phosphinopalladium was added. (1.24 g, 1.08 mmol) was added thereto, followed by heating and stirring for 4 hours. When the reaction was terminated to lower the temperature to room temperature and the solid obtained by filtration was washed with water (300mL) and ethanol (300mL) to give a compound of formula 11 (20.0g, 91% yield). MS [M + H] ⁺ = 347

[Formula 11]

Synthesis Example 3

Diamine compound of formula 12 (Compound 12) was prepared as follows.

Compound D (30.0 g, 47.2 mmol) and compound E (16.3 g, 94.4 mmol) were completely dissolved in tetrahydrofuran (250 ml), and then 1.5 M aqueous potassium carbonate solution (100 ml) was added, and tetrakistriphenyl-phosphinopalladium was added. (1.0 g, 0.87 mmol) was added and the mixture was heated and stirred for 4 hours. When the reaction was terminated to lower the temperature to room temperature and the solid obtained by filtration was washed with water (200mL) and ethanol (200mL) to prepare a compound of formula 12 (30.3g, 97% yield). MS [M + H] ⁺ = 663

[Formula 12]

<Example 1>

On one surface of the alkali-free glass as a carrier substrate, 1 mol of BPDA (3,3,4,4'-biphenyltetracarboxylic dianhydride), TFDB (2,2'-bis (trifluoromethyl)-[1,1 ' -biphenyl] -4,4'-diamine) 20% by weight of a polyamic acid resin prepared by polymerizing 0.5mol and 0.5mol of the diamine of Formula 10 prepared in Synthesis Example 1 and 80% by weight of DMAc (dimethylacetamide) as a solvent. The composition containing% was applied to a thickness of 10 μm after drying, and the resulting coating film was successively subjected to a drying step at 100 ° C. and a curing step at 300 ° C. for 60 minutes to form a polymer layer of the flexible substrate. The polyimide film for was formed.

<Example 2>

On one side of the alkali-free glass as a carrier substrate, a composition comprising 20% by weight of polyamic acid-based resin prepared by polymerizing 1 mol of BPDA and 0.99 mol of the diamine of Formula 11 prepared in Synthesis Example 2 and 80% by weight of DMAc as a solvent. After drying, the coating was applied to a thickness of 10 μm, and the resulting coating film was continuously subjected to a drying step at 100 ° C. and a curing step at 300 ° C. for 60 minutes to form a polyimide film for forming a polymer layer of the flexible substrate. It was.

<Example 3>

On one surface of an alkali-free glass as a carrier substrate, 20% by weight of a polyamic acid-based resin prepared by polymerizing 1 mol of BPDA, 0.5 mol of TFDB, and 0.5 mol of the diamine of Formula 12 prepared in Synthesis Example 3, and 80% by weight of DMAc as a solvent After drying, the composition was coated to have a thickness of 10 μm, and the resulting coating film was continuously subjected to a drying step at 100 ° C. and a curing step at 300 ° C. for 60 minutes to form a polymer for forming a polymer layer of the flexible substrate. The mid film was formed.

Comparative Example 1

On one surface of the alkali-free glass as a carrier substrate, a composition containing 20% by weight of a polyamic acid resin prepared by polymerizing 1 mol of BPDA and 0.99 mol of TFDB and 80% by weight of DMAc as a solvent was applied so as to have a thickness of 10 μm. The resulting coating film was continuously subjected to a drying step at a temperature of 100 ° C. and a curing step at 300 ° C. for 60 minutes to form a polyimide film for forming a polymer layer of a flexible substrate including a polyimide resin. .

Comparative Example 2

A polyimide film for forming a layer of the flexible substrate was prepared in the same manner as in Example 1, except that diamine (SBF) of the following formula was used.

For the films prepared in Examples 1 to 3 and Comparative Examples 1 and 2, the coefficient of thermal expansion (CTE), glass transition temperature (Tg) and thickness direction phase difference (Rth) were evaluated by the following methods, and the results are shown in Table 1 below. Indicated.

1) coefficient of thermal expansion (CTE) and glass transition temperature (Tg)

A sample with a thickness of 10 µm, a width of 5 mm, and a length of 5 cm is set to be pulled by a jig so that the measuring length becomes 16 mm, and then pulled with a force of 0.02 N, and the temperature rising rate is 5 ° C./min. After it was cooled down to 50 ° C. (primary cooling), and the temperature was further increased to 450 ° C. (secondary temperature increase), the thermal expansion value in the range of 100 to 250 ° C. was measured by TMA (Q400 of TA). At this time, the inflection point seen in the temperature increase section in the first temperature increase step was set to Tg.

2) Phase difference (Rth)

Thickness direction retardation (Rth) of the film having a thickness of 10 μm, a width of 5 cm, and a length of 5 cm was measured by Axoscan.

CTE (ppm / ℃, 100 ~ 250 ℃ @ 2 ^nd heat) Tg (℃) Rth (@ 550nm) Example 1 36.3 363 -299 Example 2 50 363 -200 Example 3 26.8 > 450 -657 Comparative Example 1 51 318 -915 Comparative Example 2 55 350 -180

From the results of Table 1, it can be seen that the polyimide film according to the present invention has a lower CTE value and a higher glass transition temperature than the polyimide of Comparative Examples 1 and 2. Especially in the case of Example 2, the CTE value is similar to that of Comparative Example 1, but has a much higher glass transition temperature. According to the present invention, by including two phenyl groups fixed and spiro or cardo group fixed in the molecular structure, it is possible to limit the movement of the phenyl group even if the temperature rises, thereby improving the dimensional stability against heat.

In contrast with Comparative Example 2, since the structure according to the present invention has a linear (linear) structure, it can be seen that it is possible to increase the Tg while minimizing the increase in CTE compared to the conventional cardo monomer.

The specific parts of the present invention have been described in detail above, and it is apparent to those skilled in the art that such specific descriptions are merely preferred embodiments, and thus the scope of the present invention is not limited thereto. something to do. Thus, the substantial scope of the present invention will be defined by the appended claims and their equivalents.

Claims (8)

A polyimide prepared from a polymerization component comprising tetracarboxylic dianhydride and a diamine selected from the following general formulas (1a) to (1e): [Formula 1a]

[Formula 1b]

[Formula 1c]

[Formula 1d]

[Formula 1e]

In Chemical Formulas 1b to 1e, R ₁ and R ₂ are each independently a hydrogen atom, a halogen atom, 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, It is a substituent chosen from the halogeno alkoxy of C1-C4, the halogenoalkyl of C1-C10, and the aryl group of C6-C20. The method of claim 1, Wherein the polymerization component is a polyimide containing a diamine selected from the formula 1a to 1e with respect to the total content of the diamine in an amount of 30 to 100 mol%. The method of claim 1, The polyimide whose thermal expansion coefficient (CTE) of the said polyimide is 50 ppm / degrees C or less. The method of claim 1, The polyimide whose glass transition temperature (Tg) of the said polyimide is 330 degreeC or more. The method of claim 1, Polyimide wherein the polymerization component further comprises a diamine of the formula (6): [Formula 6]

In Chemical Formula 6, R ₃₁ and R ₃₂ are each independently a hydrogen atom, a halogen atom, 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, and a carbon number Selected from 1 to 4 halogenoalkoxy, halogenated alkyl of 1 to 10 carbon atoms, aryl group of 6 to 20 carbon atoms, n and m are each independently an integer of 0-4. Q ₁ is a single bond, -O-, -CR ₁₈ R _19- , -C (= O)-, -C (= O) O-, -C (= O) NH-, -S-, -SO ₂ -A phenylene group 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 Will be. The polyimide film for flexible elements containing the polyimide in any one of Claims 1-5. The polyimide substrate for oxide TFT or LTPS containing the polyimide of any one of Claims 1-5. Diamine represented by any one selected from formulas 1a to 1e: [Formula 1a]

[Formula 1b]

[Formula 1c]

[Formula 1d]

[Formula 1e]

In Chemical Formulas 1b to 1e, Wherein R _1, R ₂ each independently represent a hydrogen atom or a halogen atom, a hydroxyl group (-OH), thiol (-SH), a nitro group (-NO _2), a cyano group, an alkyl group having 1 to 10 carbon atoms, It is a substituent chosen from the halogeno alkoxy of 1-4, the halogenoalkyl of 1-10 carbon atoms, and the aryl group of 6-20 carbon atoms.