KR102020091B1

KR102020091B1 - Polyimide precursor resin solution and transparent polyimide film prepared by using same

Info

Publication number: KR102020091B1
Application number: KR1020150179944A
Authority: KR
Inventors: 윤철민; 김경준
Original assignee: 주식회사 엘지화학
Priority date: 2015-12-16
Filing date: 2015-12-16
Publication date: 2019-10-18
Also published as: KR20170071812A

Abstract

The present invention can provide a polyimide precursor composition containing a diammonium salt, the polymerization reaction can proceed faster than using a general diamine structure, it is possible to shorten the production time of the polyimide film, side reactions during the polymerization process By reducing the higher molecular weight polyamide film can be provided.

Description

Polyimide precursor composition and transparent polyimide film made therefrom {POLYIMIDE PRECURSOR RESIN SOLUTION AND TRANSPARENT POLYIMIDE FILM PREPARED BY USING SAME}

The present invention relates to a polyimide precursor composition capable of producing a transparent polyimide film.

In general, glass substrates are used in flat panel displays (FPDs), such as plasma displays, liquid crystal display, and organic light emitting display. As displays using such glass substrates become thinner and smaller in size, transparent plastic substrates are being investigated for glass substrate replacement.

In particular, in the case of a cover coating layer that can protect the display from impact or scratches, conventionally, tempered glass or an organic-inorganic composite having excellent surface hardness has been used. However, these materials are very inflexible and have the disadvantage of being broken by folding.

Substrate using a polyethylene terephthalate (PET) film or polyether sulfone (PES) film has been developed as a transparent plastic substrate for glass substrate replacement. The PET film or PES film is a film of a transparent polymer resin. The transparent plastic substrate using the polymer resin film has good ductility compared to the glass substrate, but has low heat resistance because of low glass transition temperature (Tg). In addition, since the coefficient of thermal expansion (CTE) is larger than that of the glass substrate, deformation occurs easily in a process made at a high temperature (for example, a TFT process of 220 ° C or higher) in the display manufacturing process. Therefore, the development of a transparent plastic substrate material having high heat resistance and low coefficient of thermal expansion while showing transparency as a glass substrate is required, and various studies have been made.

Since polyimide has excellent heat resistance, chemical resistance, radiation resistance, electrical insulation, mechanical properties, and the like, a polyimide substrate, a tape automation bonding substrate, a semiconductor device protective film, and an interlayer insulating film of an integrated circuit It is currently widely used in various electronic devices. However, the polyimide not only decreases transparency due to an increase in crystallinity of the film due to crosslinking reaction between polyimide polymer chains or due to process problems such as hydrolysis, but also changes the color of the film. This is easy to fall.

Therefore, in order to use the polyimide as a transparent plastic substrate material, it is required to be excellent in mechanical properties and to simultaneously exhibit high optical properties.

It is an object of the present invention to provide a polyimide precursor composition capable of providing a polyimide-based film exhibiting excellent mechanical properties with high transparency.

Another object of the present invention is to provide a polyimide film prepared using the polyimide composition.

Still another object of the present invention is to provide a display device or a cover coating layer of the display device including the polyimide film.

In order to solve the problems of the present invention,

Provided are a polyimide precursor composition prepared by reacting a diammonium salt represented by Formula 1 and a tetracarboxylic acid represented by Formula 2, and a method of preparing the same.

[Formula 1]

[Formula 2]

In the above formula,

X is a tetravalent organic group containing an aromatic ring or an aliphatic ring structure,

Y is a divalent organic group containing an aliphatic or aliphatic ring structure,

Q is monovalent organic acid ion or inorganic acid ion.

In order to solve the other subject of this invention, the polyimide film manufactured from the said polyimide precursor composition is provided.

In addition, the present invention provides a display device including the polyimide film.

Other specific details of the embodiments of the present invention are included in the following detailed description.

The present invention can provide a polyimide precursor composition containing a diammonium salt, the polymerization reaction can proceed faster than using a general diamine structure, it is possible to shorten the production time of the polyimide film, side reactions during the polymerization process By reducing the higher molecular weight polyamide film can be produced.

Figure 1 shows a polyimide film prepared in Preparation Example 1 (a), Preparation Example 2 (b), Preparation Example 3 (c).
2 is a graph comparing the transmittance of the polyimide film prepared in Comparative Example 1 and Example 1.

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 functional 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 functional 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 hydroxyl 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- ), Ethylene groups (-CH ₂ CH _2- ) and the like, fluoroalkylene groups having 1 to 10 carbon atoms (e.g., fluoromethylene groups (-CF _2- ), perfluoroethylene groups (-CF ₂ CF _2- ); ), A hetero atom such as N, O, P, S, or Si or a functional group containing the same (specifically, intramolecular carbonyl group (-C = O-), ether group (-O-), ester group ( Or a heteroalkylene group including -COO-), -S-, -NH- or -N = N- and the like, or that two or more functional groups are condensed and connected.

The present invention provides a polyimide precursor composition prepared by reacting a diammonium salt of formula (1) and tetracarboxylic acid of formula (2).

[Formula 1]

[Formula 2]

In the above formula,

Q is monovalent organic acid ion or inorganic acid ion.

According to one embodiment, the Y may be a divalent organic group containing an aliphatic ring having 4 or more carbon atoms, preferably 6 or more carbon atoms, more preferably an alicyclic carbon atoms of 6 to 12 carbon atoms, for example cyclohexane Can be.

According to an embodiment, the Q may be selected from an inorganic acid selected from HCl, HBr, or HI, or an organic acid including a carboxyl group, a sulfone group, a sulfin group, or a phosphoric acid group, preferably acetic acid, chloroacetic acid, carbon number 1 One or more substituents containing acetic acid, benzene sulfonic acid, methane sulfonic acid, or a fluoroalkyl group having 1 to 6 carbon atoms or a fluoro atom substituted with one or more fluoroalkyl groups or substituents containing fluoro atoms It may be selected from an organic acid consisting of meta sulfonic acid and the like. More preferably, at least one selected from acetic acid or acetic acid substituted with at least one with a fluoroalkyl group having 1 to 6 carbon atoms or a substituent containing a fluoro atom, for example, Q may be acetic acid or trifluoric acid have.

According to one embodiment, the diammonium salt may be one having a trans stereostructure, as shown in the formula (1-1).

[Formula 1-1]

According to the present invention, the trans structure of Formula 1-1 may be included in 90% or more, preferably 95% or more, more preferably 98% or more of the total ammonium salt component, for example, 90% to 100% It may be included in the content of.

In general, a polyamic acid may be formed in a polymerization reaction of a polyamic acid using an acid dianhydride or a diamine containing an aliphatic or aliphatic ring structure, from which polymerization of the polyamic acid may be difficult or even if a polymerization reaction occurs. It was difficult to superpose | polymerize the polyamic acid of molecular weight, and there existed a problem that manufacture of an alicyclic polyimide film was difficult. The polyamic acid salt may precipitate without dissolving in a solvent or increase the viscosity of a polymerization solution. The polyamic acid salt may decompose over time, but the polymerization time may be very long from this, which causes a decrease in productivity.

In this case, the polyamic acid salt may be in the form of ammonium carboxylate salt formed by ion bonding of carboxylate ions and ammonium ions, which means that chemical species of diamine and tetraacid dianhydride are connected through ionic bond or polar interaction. For example, it may mean a form containing a structure of the following formula (3).

[Formula 3]

In the above formula,

X and Y are organic groups derived from Chemical Formulas 1 and 2.

Accordingly, the present invention can suppress the formation of polyamic acid salts by reacting diammonium with tetracarboxylic acid instead of diamine, which may be preferable for shortening the polymerization time and preparing a high molecular weight polyimide film. In addition, the viscosity of the polymerization solution may be reduced to improve the applicability of the polyimide precursor composition, thereby forming a more transparent and uniformly formed polyimide film. In addition, the storage stability of the polyimide precursor composition may be improved by suppressing polyamic acid salt formation, and by improving the reversible reaction of the monomer or polyamic acid which remains unreacted, thereby reducing optical and mechanical properties resulting from these problems. Can be reduced.

In addition, according to a preferred embodiment of the present invention, it may be preferable that the diammonium salt has a trans structure as shown in Formula 1-1, and the polyimide precursor composition including the trans-diammonium salt may increase polymerization reactivity. At the same time, it is possible to reduce steric hindrance, and as a result, it is possible to prepare a high molecular weight polyimide having excellent heat resistance and mechanical properties. Since the three-dimensional structure of the cis (cis) has a thermodynamically stable three-dimensional structure can reduce the polymerization reactivity, and the functional group is located in close proximity may cause a steric hindrance. As a result, it is possible to lower the mechanical properties of the polyimide film without reaching a sufficient degree of polymerization during polyamic acid production. However, in the case of having a three-dimensional structure of the trans-transformer, it is relatively advantageous to the polymerization reaction, and the ammonium group, which is a functional group, is positioned relatively far to lower the steric hindrance, thereby making it possible to polymerize a high molecular weight polyimide. It may be possible to produce this excellent transparent polyimide film.

Polyimide precursor composition according to the invention may comprise a polyamic acid of the formula (4).

[Formula 4]

In the above formula,

X and Y are organic groups derived from Chemical Formulas 1 and 2.

Using a polyimide precursor composition comprising a polyamic acid of Formula 4, a polyimide film including a repeating structure of Formula 5 is prepared.

[Formula 5]

In Chemical Formula 5,

X and Y are organic groups derived from Chemical Formulas 1 and 2.

X may be one or more tetravalent organic groups selected from alicyclic carbon atoms having 4 to 30 carbon atoms or aromatic ring structures having 6 to 24 carbon atoms, for example, monocyclic or polycyclic alicyclic, monocyclic or polycyclic It may be selected from an aromatic ring structure.

More specifically, tetravalent organic groups represented by the following Chemical Formulas 6a to 6k may be mentioned, but are not limited thereto.

In addition, the Y may be one or more divalent organic groups selected from alicyclic ring structure of 4 to 30 carbon atoms, aliphatic chain structure of 4 to 30 carbon atoms, preferably, a monocyclic or polycyclic alicyclic ring structure It may be a divalent organic group including.

More specifically, it may be one selected from the following divalent organic groups of 7a to 7h, but is not limited thereto.

In the above formula,

a1, a2, a3 are 0 or an integer of 1 or more.

Polyimide according to the present invention may further include a repeating structure of the formula (8).

[Formula 8]

In the above formula,

X ₁ is a tetravalent organic group derived from tetracarboxylic dianhydride,

Y ₁ is a divalent organic group derived from a diamine or a diammonium salt.

More specifically, X ₁ is a tetravalent organic group of an aliphatic, cycloaliphatic, or aromatic group, or a combination thereof, and a tetravalent organic group in which an aliphatic, alicyclic, or aromatic tetravalent organic group is linked to each other through a crosslinking structure is used. Carboxylic dianhydride. Preferably monocyclic or polycyclic aromatic, monocyclic or polycyclic alicyclic, or two or more of them may have a structure connected by a single bond.

X ₁ is specifically an aromatic tetravalent organic group represented by Formulas 9a to 9d; Alicyclic tetravalent organic group containing a structure of a cycloalkane having 3 to 12 carbon atoms; An alicyclic tetravalent organic group of formula (8e); It may be selected from the group consisting of aliphatic tetravalent organic groups having a branched alkan structure having 3 to 10 carbon atoms and combinations thereof:

[Formula 9a]

[Formula 9b]

[Formula 9c]

[Formula 9d]

[Formula 9e]

In Formulas 9a to 9e, R ₁₁ To R ₁₇ may be each independently an alkyl group having 1 to 10 carbon atoms or a fluoroalkyl group having 1 to 10 carbon atoms,

A ₁ is an integer of 0 to 2, a ₂ is an integer of 0 to 4, a ₃ is an integer of 0 to 8, a ₄ and a ₅ are each independently an integer of 0 to 3, a ₆ and a ₉ are each Independently an integer from 0 to 3, and a ₇ and a ₈ may be each independently an integer from 0 to 9, and A ₁₁ and A ₁₂ are each independently a single bond, -O-, -CR ₁₈ R _19- , -C (= O)-, -C (= O) NH-, -S-, -SO _2- , a phenylene group and a combination thereof may be selected from the group, wherein R ₁₈ And R ₁₉ may be each independently selected from a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, and a fluoroalkyl group having 1 to 10 carbon atoms.

More specifically the X ₁ silver It may be a tetravalent organic group selected from Formulas 10a to 10n, but is not limited thereto:

In Formulas 10a to 10n, the compounds may be independently substituted with an alkyl group having 1 to 10 carbon atoms or a fluoroalkyl group having 1 to 10 carbon atoms.

On the other hand, in Formula 8, Y ₁ is an aliphatic, alicyclic or aromatic divalent organic group derived from a diamine compound or a diammonium salt compound, or as a combination thereof, an aliphatic, alicyclic or aromatic divalent organic group is directly It may be a divalent organic group linked or linked to each other via a crosslinked structure.

For example, Y ₁ may be a monocyclic or polycyclic aromatic having 6 to 18 carbon atoms, a monocyclic or polycyclic alicyclic having 6 to 18 carbon atoms, or a structure in which two or more thereof are connected by a single bond, and more specifically, It may be a divalent organic group selected from the group consisting of a divalent organic group of formula 11a to 11e, a divalent organic group of formula 11f, a divalent organic group of formula 11g and combinations thereof:

[Formula 11a]

[Formula 11b]

[Formula 11c]

Formula 11d]

[Formula 11e]

[Formula 11f]

[Formula 11g]

In Chemical Formulas 11a to 11g,

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.) It may be selected from the group consisting of, preferably each independently may be a methyl group,

R ₃₁ to R ₃₈ each independently represent 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 it may be selected from the group consisting of a phenyl group, preferably each independently may be a hydrogen atom, a methyl group or a phenyl group,

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 (for example, 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-, 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 (for example, a phenylene group, naphthalene group, fluorenylene group, etc.), and combinations thereof may be selected. Can,

A ₂₃ is-[CR'R "-CH ₂ O] _z- , 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, iso Propyl group, n-butyl group, tert-butyl group, pentyl group and the like) and haloalkyl group having 1 to 10 carbon atoms (for example, trifluoromethyl group, etc.), and z is 1 to 8 Is an integer, and

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 An integer of 1, b ₇ and b ₈ are each independently an integer of 0 to 10, and m and n may be each independently an integer of 1 to 15.

In addition, when Y ₁ in Formula 8 is a combination group, specifically, at least two of aliphatic, aromatic, or alicyclic structures are directly connected, or -O-, -CR'R "-(wherein R 'and R" Are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms (for example, a methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, tert-butyl group, pentyl group, etc.) and halo having 1 to 10 carbon atoms. Alkyl group (e.g., trifluoromethyl group, etc.), -C (= 0)-, -C (= 0) O-, -C (= 0) 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., cyclohexylene group), a monocyclic or polycyclic arylene group having 6 to 18 carbon atoms (e.g., phenylene group, naphthalene group , Fluorenylene group, and the like), and combinations thereof A second derived from a diamine comprising a structure associated with may be an organic group.

According to a preferred embodiment of the present invention, Formula 8 may include a structure in which at least one of X ₁ and Y ₁ includes a fluoro-based substituent. As used herein, the term "fluoro-based substituent" means both a "fluoro atom substituent" and a "substituent containing a fluoro atom." The fluoro-based substituent may be a fluoro alkyl group having 1 to 10 carbon atoms or 1 to 6 carbon atoms, and may be contained in an amount of 0.1 to 10 mol parts with respect to 100 mol parts of the polyimide repeating structure of Formula 5, preferably 0.1 It may be contained in a mole part to 6 mole parts, more preferably 0.1 mole part to 3 mole parts.

The diammonium salt of Formula 1 and tetracarboxylic dianhydride of Formula 2 are preferably used in an appropriate reaction ratio in consideration of the physical properties of the polyimide to be finally prepared. Specifically, the diammonium salt compound may be used in a molar ratio of about 0.9 to 1.1 with respect to 1 mole of the tetracarboxylic dianhydride, and preferably 0.95 to 1.05 molar ratio. If the content ratio is out of the above range, the imidation rate or molecular weight of the polyimide to be produced is low, there is a fear that film formation becomes difficult.

In addition, in the case of the polyimide further including a repeating structure of Formula 8, total diammonium salt and / or diamine may be used in a molar ratio of about 0.9 to 1.1 with respect to 1 mol of total tetracarboxylic dianhydride, preferably 0.95 It may be desirable to have a molar ratio of 1.05 to 1.05.

The polyimide precursor polymerization reaction can be carried out according to a polymerization method of ordinary polyimide or a precursor thereof, such as solution polymerization.

The organic solvent usable in the polymerization reaction is specifically N, N-dimethylacetamide, N, N-diethylacetamide, N-methylpyrrolidone, N-ethylpyrrolidone, N, N-dimethylformamide , N, N-diethylformamide 1,3-dimethyl-2-imidazolidinone, N, N-dimethylmethoxyacetamide, dimethyl sulfoxide, pyridine, dimethyl sulfone, hexamethylphosphoamide, tetramethylurea , N-methylcaprolactam, tetrahydrofuran, m-dioxane, P-dioxane, 1,2-dimethoxyethane, bis (2-methoxyethyl) ether, 1,2-bis (2-methoxye Methoxy) ethane, bis [2- (2-methoxyethoxy)] ether, and the like, and one or a mixture of two or more thereof may be used. For example, N, N-dimethylacetamide, N, N-diethylacetamide, N-methylpyrrolidone, N-ethylpyrrolidone, N, N-dimethylformamide, N, N-diethylform One or more solvents selected from amide 1,3-dimethyl-2-imidazolidinone, N, N-dimethylmethoxyacetamide can be used.

In addition, the polymerization reaction of the polyimide precursor is at a temperature of less than about 10 to 50 ℃, or a temperature of about 15 to 40 ℃, preferably at a temperature of 20 to 30 ℃, or room temperature, about 10 to 50 hours, or about It may be desirable to conduct the polymerization reaction for 15 to 40 hours, preferably 20 to 40 hours.

The present invention can suppress the formation of polyamic acid salts, which can be formed by side reactions during the production of polyimide precursors, by using a diammonium salt structure rather than a diamine structure to prepare polyimide precursors. Since the time can be saved, the time taken for the polymerization reaction can be 1.5 times or more, preferably 2 times, more preferably 3 times or more, compared to the existing process. Three days or more, that is, 72 hours or more time was required, but the polymerization reaction according to the present invention may take less than one day, that is, less than 24 hours, to complete the polymerization reaction.

As a result of the polymerization reaction, a polyamic acid of the formula (4) is prepared. The viscosity of the polyimide precursor composition comprising the polyamic acid may be 5,000 cP to 100,000 cP. The prepared polyamic acid may be imidized to prepare a polyimide solid, and then a film forming composition may be prepared. However, it is preferable to prepare a composition for forming a polyimide film by further adding a solvent to the prepared polyamic acid solution. Can be.

Specifically, the solution for forming a polyimide film prepared according to the above-described manufacturing method includes a solid content in an amount such that the composition for film formation has an appropriate viscosity in consideration of processability such as coating property during film forming process. desirable. According to one embodiment, the content of the composition may be adjusted so that the content of the polyamic acid is 5 to 25% by weight, preferably 5 to 20% by weight, more preferably 5 to 20% by weight, or 5 to 15%. The weight can be adjusted to below.

Alternatively, the polyimide film-forming composition may be adjusted to have a viscosity of 500 cP or more, or 1,000 cP or more, preferably 3,000 cP or more, and the viscosity of the polyimide film forming composition is 30,000 cP or less, or 20,000. It is preferable to adjust to have a viscosity of cP or less, preferably 18,000 cP or less, or 15,000 cP or less. If the viscosity of the composition for forming a polyimide film is less than 500 cP or exceeds 30,000 cP, the foaming and surface roughness may not be good at the time of processing the polyimide film, and thus the optical properties may be reduced.

Subsequently, by imidating the polyamic acid obtained as a result of the polymerization reaction, a polyimide including a repeating structure of Formula 5 or a complex repeating structure of Formulas 5 and 8 may be prepared. In this case, the imidization process may specifically include a chemical imidization method or a thermal imidization method, and a heat imidation method may be used as a preferred embodiment of the present invention.

The method for manufacturing a polyimide film using the prepared composition includes applying the polyimide film-forming composition to one surface of a substrate and separating the substrate from the substrate after the imidization and curing processes.

The polyimide film-forming composition may further include additives such as a binder, a solvent, a crosslinking agent, an initiator, a dispersant plasticizer, a viscosity modifier, an ultraviolet absorber, a photosensitive monomer, or a sensitizer, which are usually used for forming a polyimide film. have.

Next, a polyimide-based film may be prepared by applying the polyimide-based solution prepared above to one surface of a substrate, heat imidizing and curing at a temperature of 80 to 300 ° C., and then separating from the substrate.

In this case, a glass, a metal substrate, or a plastic substrate may be used without particular limitation, and among these, excellent thermal and chemical stability during the imidization and curing process for the polyimide precursor, and after curing, without a separate release agent treatment Glass substrates that can be easily separated without damage to the polyimide-based film formed may be desirable.

In addition, the coating step may be carried out 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, dipping method, brushing method and the like can be used. Of these, the continuous process is possible, and it may be more preferable to be carried out by a casting method that can increase the imidation ratio of the polyimide resin.

In addition, the polyimide-based solution may be applied on the substrate in a thickness range such that the polyimide-based film to be produced has a thickness suitable for the display substrate. Specifically, it may be applied in an amount such that it becomes a thickness of 10 to 50㎛.

After applying the composition for forming a polyimide film, a drying step for removing the solvent present in the composition for forming a polyimide film may be optionally further performed before the curing step.

The drying process may be carried out according to a conventional method, specifically may be carried out at a temperature of 140 ℃ or less, or 80 to 140 ℃. If the implementation temperature of a drying process is less than 80 degreeC, a drying process will become long, and when it exceeds 140 degreeC, imidation will advance rapidly and it will be difficult to form polyimide film of uniform thickness.

Subsequently, the thermal imidization and curing process may be performed by heat treatment at a temperature of 50 to 300 ° C., preferably 60 to 280 ° C., more preferably 80 ° C. to 300 ° C. According to one embodiment, the curing process may be carried out by a multi-stage heating treatment at various temperatures within the above temperature range. For example, primary heating at 60 ° C. to 100 ° C. for 5 to 20 minutes; Secondary heating at 100 ° C. to 200 ° C. for 15 minutes to 1 hour; It may include the step of third heating at 200 ℃ to 300 ℃ for 30 minutes to 2 hours. In addition, the total curing time in the curing process is not particularly limited, and as an example, may be carried out for a total time of 15 minutes to 4 hours, preferably 3 hours or less, more preferably 2 hours or less.

In addition, after the imidization and curing process, a subsequent heat treatment step may be optionally further performed to increase the imidation ratio of the polyimide resin in the polyimide film to form a polyimide film having the above-described physical properties. have.

The subsequent heat treatment process is preferably carried out at 200 ° C or more, or 200 to 300 ° C for 1 to 60 minutes. In addition, the subsequent heat treatment process may be performed once or may be performed in multiple stages two or more times. Specifically, it may be carried out in three steps including a first heat treatment at 200 to 220 ° C., a second heat treatment at 220 to 250 ° C., and a third heat treatment at 250 to 300 ° C.

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

Polyimide After film coating a composition comprising a polyimide polyamic acid made from a composition for forming a conducting the imidization in more than 500 ℃ temperature IR spectrum of 1350 to 1400cm according to the ^invention ¹ or 1550 to 1650cm ^{- With} respect to 100% of the integrated intensity of the CN band represented by ¹ , the relative integrated intensity ratio of the CN band after imidization at a temperature of 200 ° C. or higher is about 60% to 99%, or about 70%, based on the imidation ratio. It may have an imidation ratio of about 98%, or about 75% to 96%.

In addition, the polyamic acid or polyimide precursor 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 polyamic acid or polyimide precursor according to the present invention is preferably 1.1 to 2.5. If the imidation ratio of the polyimide, the weight average molecular weight or the molecular weight distribution of the polyimide precursor are out of the above ranges, film formation may be difficult or the characteristics of the polyimide film such as permeability, heat resistance and mechanical properties may be deteriorated. .

The present invention can suppress the production reaction of the polyamic acid salt formed by the polar bond of the ammonium salt and carboxylic acid salt by using the diammonium salt of formula (1) in the production of polyamic acid. In the conventional process, the time until the polar bond is dissociated by the formation of the polyamic acid salt is delayed and the chain of the polyamic acid does not grow long due to the formation of the polyamic acid salt. Due to this formation, thermal properties such as mechanical properties and heat resistance may be lowered. The present invention can provide a polyimide film having a higher molecular weight by providing a method capable of suppressing the formation of such a polyamic acid salt.

Polyimide according to the present invention may have a glass transition temperature of about 200 ℃ or more. Since it has such excellent heat resistance, the film containing the said polyimide can maintain the outstanding heat resistance and transparency with respect to the high temperature heat added during an element manufacturing process.

In addition, the polyimide-based film has a haze (Haziness) 2 or less, the transmittance of light with a wavelength of 380 to 760nm in the film thickness range of 10 to 50㎛ 80% or more, yellowness (YI) is about 7 or less, More preferably, it may be a colorless transparent polyimide film, which is about 5 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 a modulus of about 4 GPa or more, or about 4.5 to 10 GPa, a maximum stress value of about 200 to 400 MPa, or about 230 to 350 MPa, and a maximum elongation of about 10 to 100%. Or polyimide-based film having excellent mechanical properties of about 10 to 45%, or about 10 to 30%.

The film may have a dimension change at 250 ° C. of less than 200 μm, or 170 μm or less, or 150 μm or less. The smaller the dimensional change is preferable, but according to one embodiment, the dimensional change may be 50 μm or more, or 80 μm or more.

In addition, the polyimide film may have a coefficient of thermal expansion (CTE) of about 40 ppm or less, or about 30 ppm / ° C. or less at a temperature of 100 ° C. to 200 ° C., and a coefficient of thermal expansion upon cooling. It may be a high heat-resistant polyimide film having a value of 40 ppm / ℃ or less in the range of 300 ℃ to 100 ℃.

In addition, by using the polyimide-based film as a display substrate, it is possible to suppress the occurrence of warpage and the deterioration of the reliability of other devices during the process of manufacturing the device on the display substrate, and as a result the device having improved characteristics and reliability It is possible to manufacture. Accordingly, the polyimide may be particularly useful for the manufacture of flexible substrates in electronic devices such as OLEDs or LCDs, electronic papers, and solar cells.

The polyimide film manufactured by the above method may be usefully used as a hard cover layer of a display device requiring high transparency, excellent heat resistance, mechanical strength, and isotropy.

Accordingly, according to another embodiment of the present invention, a display device and a device including the polyimide-based film may be provided.

Specifically, the device may be any flexible solar cell (eg, flexible solar cell), organic light emitting diode (OLED) illumination (eg, flexible OLED light), any semiconductor device having a flexible substrate, Or a flexible display device such as an organic light emitting display device, an electrophoretic device, or an LCD device, and a hard cover layer of the display device.

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.

Preparation Example 1 Polyamic Acid (trans-CHDAA / BPDA)

After dissolving 1 mol of Trans-CHDA (Trans-1,4-cyclohexane diamine) in DMAc, adding 2 mol of Acetic acid and stirring it at room temperature sufficiently, 1 mol of BPDA was added to the solution where white precipitate was formed and polymerized for 48 hours. The solution was prepared.

Preparation Example 2 Polyamic Acid (cis-CHDAA / BPDA)

After dissolving 1 mol of cis-CHDA in DMAc, 2 mol of acetic acid was added thereto, and the mixture was sufficiently stirred at room temperature. Then, 1 mol of BPDA was added to a solution having a white precipitate to polymerize for 48 hours to prepare a polyimide precursor solution.

Preparation Example 3 Polyamic Acid (isomer-CHDAA / BPDA)

Dissolve 1mol CHDA mixed with Isoemr-CHDA and cis-CHDA in DMAc, add 2mol of Acetic acid and stir at room temperature sufficiently, add 1mol of BPDA to white precipitate solution, and polymerize for 48 hours. Prepared.

Experimental Example 1 Comparison of Molecular Weight According to Isomer Structure

The solution is further added so that the solid content of each of the polyimide precursor solutions prepared in Preparation Examples 1 to 3 is 14 wt%, and the polyimide precursor solutions prepared in Preparation Examples 2 and 3 have a 20 wt% solids content. The solution was further added to prepare a film composition. The viscosity of the prepared polyimide precursor solution was measured and shown in Table 1 below.

Each prepared polyimide precursor solution was spin coated onto a glass substrate to a thickness of 20 to 30 μm. The glass substrate coated with the polyimide precursor solution was placed in an oven and heated at a rate of 2 ° C./min, and the curing process was performed by maintaining 15 minutes at 80 ° C., 30 minutes at 150 ° C., and 1 hour at 250 ° C. After completion of the curing process, the film formed on the glass substrate was peeled off. The prepared film is shown in FIG. 1, and the molecular weight of the polyimide included in the film was measured and shown in Table 1.

division Preparation Example 1 Preparation Example 2 Preparation Example 3 Viscosity (cP) 18,200 9,700 6,200 Polyimide Molecular Weight (Mw) 49,000 37,000 29,000

The polyimide precursor composition of Preparation Example 3 prepared with CHDAA having an isomer structure showed the lowest viscosity, and the polyimide precursor composition prepared with CHDAA having a cis structure also exhibited low viscosity. In addition, the polyimide of Preparation Example 1 prepared with CHDAA containing a homogeneous isomer of Trans showed a higher molecular weight than that of the isomer and cis structures. In the case of the cis and isomer CHDA structure, molecular weight is not higher than trans due to steric hindrance. The viscosity may appear low. Therefore, it may be difficult to obtain a film of high strength when the polymerization is performed in-situ in the presence of an isomer of CHDAA. By purifying and using only trans-type CHDAA, this invention can not only polymerize a high molecular weight polyimide but also can manufacture polyimide which is excellent in the moldability of a film because of strong intermolecular interaction.

< Example 1: Preparation of polyamic acid (trans- CHDAA + BPDA ) precursor / DMAc >

As a diamine compound, 25.4 g of Trans-1,4-cyclohexane diammonium acetate (CHDAA) was dispersed in 200 g of DMAc (dimethylaceteamide) for 10 minutes under a nitrogen atmosphere. 32 g of 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (3,3', 4,4'-Biphenyltetracarboxylic dianhydride) was added to the resulting trans-CHDAA / DMAc solution as an acid anhydride compound. BPDA / DMAc solution prepared by dissolving in 160 g of DMAc was added and reacted at 25 ° C. for 36 hours. DMAc was added to the resulting reaction solution to adjust the solids to 13 wt%, and then uniformly mixed for 24 hours to prepare a polyimide precursor solution.

The prepared polyimide precursor solution was spin coated on a glass substrate to a thickness of 20 to 25 μm. The glass substrate coated with the polyimide precursor solution was placed in an oven and heated at a rate of 2 ° C./min, and the curing process was performed by maintaining 15 minutes at 80 ° C., 30 minutes at 150 ° C., and 1 hour at 250 ° C. After completion of the curing process, the film formed on the glass substrate was peeled off.

< Example 2: polyamic acid (trans- CHDAA + BPDA ) precursor preparation / NMP >

As a diamine compound, 25.4 g of Trans-1,4-cyclohexane diammonium acetate (CHDAA) was dispersed in 200 g of N-methylpyrrolidone (NMP) for 10 minutes under a nitrogen atmosphere. In the resulting trans-CHDAA / NMP solution, 32 g of 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (3,3', 4,4'-Biphenyltetracarboxylic dianhydride) was added as an acid anhydride compound. A BPDA / NMP solution prepared by dissolving in 160 g of NMP was added and reacted at 25 ° C. for 36 hours. NMP was added to the resulting reaction solution to adjust the solids to 13% by weight, and then uniformly mixed for 24 hours to prepare a polyimide precursor solution.

< Comparative Example 1: Preparation of polyamic acid (trans- CHDA + BPDA ) precursor / NMP >

As a diamine compound, 15.5 g of Trans-1,4-cyclohexane diamine (CHDA) was dispersed in 200 g of N-methylpyrrolidone (NMP) for 10 minutes under a nitrogen atmosphere. 32 g of 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (3,3', 4,4'-Biphenyltetracarboxylic dianhydride) was added to the resulting trans-CHDA / NMP solution as an acid anhydride compound. BPDA / NMP solution prepared by dissolving in 160 g of NMP was added and reacted at 25 ° C. for 36 hours. NMP was added to the resulting reaction solution to adjust the solids to 13% by weight, and then uniformly mixed for 24 hours to prepare a polyimide precursor solution.

The prepared polyimide precursor solution was spin coated on a glass substrate with a thickness of 20 to 25 μm. The glass substrate coated with the polyimide precursor solution was placed in an oven and heated at a rate of 2 ° C./min, and the curing process was performed by maintaining 15 minutes at 80 ° C., 30 minutes at 150 ° C., and 1 hour at 250 ° C. After completion of the curing process, the film formed on the glass substrate was peeled off.

Experimental Example 2

For each polyimide film prepared in Examples 1, 2 and Comparative Example 1, optical properties of films such as transmittance, yellowness and coefficient of thermal expansion were measured in the following manner. The measurement results are shown in Table 2.

The transmittance was measured by a transmittance meter (model name HR-100, manufactured by Murakami Color Research Laboratory) according to JIS K 7105. Figure 2 shows the comparison of the transmittance according to the wavelength of the film prepared in Example 1 and Comparative Example 1.

Yellowness Index (YI) was measured using a color difference meter (Color Eye 7000A).

division Example 1 Example 2 Comparative Example 1 Thickness (㎛) 21 21 21 Haze 1.46 1.99 2.13 Yellow Degree (YI) 4.1 7.0 7.8 Transmittance (%)
(T _ave. _{(550 nm)} ) 85.3 83.4 83.3

As described above in detail specific parts of the present invention, 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. Therefore, the substantial scope of the present invention will be defined by the appended claims and their equivalents.

Claims

A polyimide precursor composition prepared by reacting a diammonium salt having a trans stereostructure of Formula 1-1 and a tetracarboxylic dianhydride represented by Formula 2 below:
[Formula 1-1]

[Formula 2]

In the above formula,
X is a tetravalent organic group containing an aromatic ring or an aliphatic ring structure,
Y is a divalent organic group having an aliphatic ring structure having 4 or more carbon atoms,
Q is monovalent organic acid ion or inorganic acid ion.

delete

The method of claim 1,
Acetic acid, benzene sulfonic acid, methanesulfonic acid, or a fluoroalkyl group having 1 to 6 carbon atoms, wherein Q is substituted with one or more substituents containing acetic acid, chloroacetic acid, a fluoroalkyl group having 1 to 6 carbon atoms, or a fluoro atom, or A polyimide precursor composition, wherein the polyimide precursor composition is one or more selected from organic acid ions consisting of metasulfonic acid with one or more substituents containing fluoro atoms.

delete

The method of claim 1,
The polyimide precursor composition wherein X is a tetravalent organic group including an aromatic ring having 6 or more carbon atoms, an alicyclic ring having 4 or more carbon atoms, or a combination thereof.

A polyimide film made of the polyimide precursor composition of any one of claims 1, 3 and 5 and comprising a repeating structure represented by the following formula (5):
[Formula 5]

In the above formula,
X is a tetravalent organic group containing an aromatic ring or an aliphatic ring structure,
Y is a divalent organic group which has a C4 or more aliphatic ring structure.

The method of claim 6,
The polyimide film having a transmittance of 80% or more for light having a wavelength of 380 to 760 nm when the polyimide film has a thickness of 10 μm or more.

The method of claim 6,
The polyimide film whose yellowness (YI) is seven or less.

The method of claim 6,
A colorless transparent polyimide film having a haze value of 2 or less.

The method of claim 6,
The polyimide film is a polyimide film further comprises a polyimide repeating structure represented by the following formula (8):
[Formula 8]

In the above formula,
X ₁ is an aliphatic, alicyclic or aromatic tetravalent organic group,
Y ₁ is an aliphatic, alicyclic or aromatic divalent organic group,
At least _one of X ₁ and Y ₁ includes a fluoro substituent.

In the method for producing the polyimide precursor composition of any one of claims 1, 3 and 5,
Method of preparing a polyimide precursor composition comprising the step of polymerizing the diammonium salt of Formula 1-1 and tetracarboxylic dianhydride of Formula 2 in a polymerization solvent to produce a polyamic acid of Formula 4 below:
[Formula 4]

In the above formula, X and Y are the same as those of the formulas (1-1) and (2).

The method of claim 11,
Method for producing a polyimide precursor composition is the polymerization reaction is carried out for 10 to 50 hours.

A display device comprising the polyimide film of claim 6.

The method of claim 13,
Display device comprising the polyimide film as a cover coating layer.