KR20160067413A - Polyimide-based solution and polyimide-based film prepared by using same - Google Patents

Abstract

The present invention may produce a polyimide-based solution including: polyimide with a structure of chemical formula 1 or a precursor thereof and a solvent, wherein a distribution coefficient (LogP value) of the solvent is a positive number at 25°C, and a polyimide-based film having high adhesion with good heat resistance and a high mechanical property. In chemical formula 1, X is selected from a group comprising an aromatic tetravalent organic group derived from an acid dianhydride and Y is selected from a group comprising an aromatic divalent organic group derived from diamine including an amino group at a para-position.

Description

POLYIMIDE BASED SOLUTION AND POLYIMIDE BASED FILM PREPARED BY USING SAME Technical Field [1] The present invention relates to a polyimide-

The present invention relates to a polyimide precursor composition, a method of manufacturing a display substrate using the same, and a display substrate, and more particularly, to a polyimide precursor composition which is excellent in heat resistance and has excellent adhesion to a glass substrate or inorganic sacrificial layer Based film.

Flexible devices are typically manufactured on the basis of high temperature thin film transistor (TFT) processes. Although the process temperature may vary depending on the types of the semiconductor layer, the insulating film, and the barrier layer included in the device during the manufacture of the flexible device, a temperature of about 300 to 500 ° C is generally required in the TFT process. However, the polymer material capable of withstanding such a processing temperature is extremely limited, and polyimide known to have excellent heat resistance is mainly used.

The flexible device is usually manufactured by applying a polyimide precursor on a carrier substrate, curing the film to form a film, and then removing the completed device from the carrier substrate through a subsequent process.

On the other hand, a flexible device accompanied by a high-temperature process is required to have heat resistance at high temperatures. In particular, in the case of an organic light emitting diode (OLED) device using a low temperature polysilane (LTPS) process, the process temperature may approach 500 ° C. However, at such a temperature, even a polyimide having excellent heat resistance tends to undergo thermal decomposition.

In addition, the above-mentioned thermosetting process consumes a considerably long curing time in order to enhance the adhesive strength between the glass substrate and the PI, and such a long thermosetting time may be one factor for increasing the processing time.

Therefore, there is a need for the development of a polyimide which can exhibit excellent chemical resistance and storage stability by preventing hydrolysis for the production of a flexible device, and which can exhibit excellent thermal stability at high temperature with sufficient mechanical properties.

An object of the present invention is to provide a polyimide-based solution capable of providing a polyimide-based film with high heat resistance and excellent mechanical properties.

Another object of the present invention is to provide a method for producing a film using the polyimide-based solution.

It is another object of the present invention to provide a device comprising a substrate made using the polyimide-based film.

The polyimide-based solution according to one aspect of the present invention comprises A polyimide having a structure represented by the following formula (1) or a precursor thereof and a solvent, wherein the solvent is a polyimide-based solution having a distribution coefficient (LogP value) at 25 캜 being a positive number.

 [Chemical Formula 1]

In Formula 1,

X is selected from the group consisting of an aromatic tetravalent organic group derived from an acid dianhydride,

And Y is an aromatic divalent organic group derived from a diamine containing an amino group at the para position.

According to one embodiment, the solvent may be a tertiary amine substituted with an alkyl group having two or more carbon atoms, and more preferably, the solvent may be a tertiary amine having two or more alkyl groups having 2 to 6 carbon atoms.

According to one embodiment, the solvent may comprise N, N-diethylacetamide, N, N-diethylformamide, N-ethylpyrrolidone or a mixture thereof.

According to one embodiment, Y may be an aromatic bifunctional unit derived from a diamine selected from the group consisting of the following formulas (4a) to (4d).

[Chemical Formula 4a]

(4b)

[Chemical Formula 4c]

[Chemical formula 4d]

Each of R ₅₁ to R ₅₅ independently represents an alkyl group having 1 to 10 carbon atoms, a fluoroalkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, a sulfonic acid group or a carboxylic acid group,

The a _2, d _2, e ₂ are each independently a ₂ is an integer of 0 to 4, b ₂ is an integer from 0 to 6, and c ₂ may be an integer of 0 to 3,

A ₂ is a single bond, -O-, -CR ₅₆ R ₅₇ -, -C (= O) -, -C (= O) NH-, -S-, -SO ₂ - , Wherein R ₅₆ and R ₅₇ are each independently selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, and a fluoroalkyl group having 1 to 10 carbon atoms.

According to one embodiment, the Y is a divalent organic compound derived from a diamine of p-phenylenediamine, 4,4'-oxydianiline or benzidine, Lt; / RTI >

According to one embodiment, the polyimide or polyimide precursor of Formula 1 is formed by the polymerization reaction of an acid dianhydride and a diamine, and the diamine may be 20 to 60% by weight based on 100 weight of the total acid dianhydride.

According to one embodiment, the polyimide-based solution may have a solids content of 10 wt% or more and 25 wt% or less based on the total weight of the solution.

According to one embodiment, the polyimide precursor composition is coated on a glass substrate and cured at a temperature of 450 ° C or higher. The film thus formed is allowed to stand at 20 ° C and 50% for 1 day, and then measured by the KS M ISO B510 method N / cm, and may have an adhesive strength of 0.1 N / cm or more when measuring the adhesive strength after the film is left for 7 days.

In order to solve the other problems of the present invention, it is possible to provide a method for producing a polyimide-based film comprising applying and curing a polyimide-based solution to one surface of a substrate and then separating the solution from the substrate.

According to one embodiment, the curing process is performed at a temperature of 450 ° C or higher, and the total time of the curing process may be 200 minutes or less.

Further, a polyimide-based film produced by the above production method can be provided.

According to one embodiment, the 1% thermal decomposition temperature (T _d1% ) of the polyimide-based film may be 550 ° C or higher.

According to one embodiment, the polyimide-based film may exhibit a thermal expansion coefficient of 5 ppm / 占 폚 or less in the range of 100 to 450 占 폚.

According to one embodiment, the tensile strength may be 300 MPa or more, the maximum elongation may be 10% or more, and the tensile elastic modulus may be 5 GPa or more.

In order to solve still another problem of the present invention, it is possible to provide a display substrate including a polyimide-based film and a device including the polyimide-based film.

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

The polyimide-based film according to the present invention is excellent as a substrate in a solar cell, an organic light emitting diode, a semiconductor device, or a flexible display device by providing an excellent adhesion to a glass substrate or an inorganic sacrificial layer together with high heat resistance and excellent mechanical properties can do.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

In the present specification, all the compounds or functional groups 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, Substituted with a substituent selected from the group consisting of an alkoxy group having 1 to 10 carbon atoms, a carboxylic acid group, an aldehyde group, an epoxy group, a cyano group, a nitro group, an amino group, a sulfonic acid group and derivatives thereof.

In the present specification, "a combination thereof" means a compound wherein at least two functional groups are a single bond, a double bond, a triple bond, an alkylene group having 1 to 10 carbon atoms (for example, a methylene group (-CH ₂ -), Ethylene group (-CH ₂ CH ₂ -)), a fluoroalkylene group having 1 to 10 carbon atoms (for example, a fluoromethylene group (-CF ₂ -), a perfluoroethylene group (-CF ₂ CF ₂ - ), A hetero atom such as N, O, P, S, or Si, or a functional group containing the same (specifically, a carbonyl group (-C═O-), an ether group (-O-), an ester group -COO-), -S-, -NH- or -N = N-), or two or more functional groups are condensed and connected.

The present invention relates to a polyimide-based solution comprising a polyimide having a structure represented by the following formula (1) or a precursor thereof and a solvent, wherein the solvent has a distribution coefficient (LogP value) at 25 캜 being positive:

[Chemical Formula 1]

In Formula 1,

X is selected from the group consisting of an aromatic tetravalent organic group derived from an acid dianhydride,

And Y is an aromatic divalent organic group derived from a diamine containing an amino group at the para position.

The partition coefficient can be calculated using the ACD / LogP module of the ACD / Percepta platform of ACD / Labs. The ACD / LogP module can calculate the quantitative structure-property relationship (QSPR) .

The present invention also provides a method for producing a polyimide-based film comprising applying the polyimide-based solution to one surface of a substrate, curing the substrate, and separating the solution from the substrate.

The present invention also provides a display substrate comprising the above polyimide-based film.

The present invention also provides an element comprising the above-mentioned polyimide-based film.

Hereinafter, a polyimide-based solution according to an embodiment of the present invention, a polyimide-based film using the same, a method for producing the same, and a display substrate and an element including the polyimide-based film will be described in detail.

According to an embodiment of the present invention, there is provided a polyimide-based solution comprising a polyimide having a structure represented by the following formula (1) or a precursor thereof and a solvent, wherein the solvent has a distribution coefficient (LogP value) / RTI >

[Chemical Formula 1]

In Formula 1,

X is selected from the group consisting of an aromatic tetravalent organic group derived from an acid dianhydride,

And Y is an aromatic divalent organic group derived from a diamine containing an amino group at the para position.

The polyimide-based solution according to the present invention is an ACD / LogP module of the ACD / Percepta platform of ACD / Labs, wherein the ACD / LogP module is a quantitative structure-property relationship (QSPR) ) Is a solvent having a distribution coefficient (Log P value) at 25 캜 is positive. More specifically, the partition coefficient LogP value may be 0.01 to 3, or 0.1 to 2, or 0.1 to 1.

Generally, as a method of increasing the adhesion of a polyimide film without using an adhesion promoter, a method in which a silane-based monomer or a monomer having a carbonyl group is directly bonded to a polyimide structure to form a polyimide structure A regulating method has been used. However, such a method may cause a problem of reducing the heat resistance and the mechanical properties of the polyimide-based film produced.

According to the studies of the present inventors, when a solution of a polyimide or a precursor thereof is prepared by using a hydrophobic solvent having a positive distribution coefficient, the dispersibility of the polyimide precursor in the solvent is increased, and amorphous polyimide- As a result, an effect of improving the adhesive strength of the resulting film can be obtained. Therefore, the polyimide prepared by using the above-described polyimide-based solution has high heat resistance and mechanical properties, and has an excellent adhesive force, thereby making it possible to manufacture a substrate having improved adhesion between the glass substrate and the inorganic sacrificial layer and the film have.

 According to a preferred embodiment of the present invention, the hydrophobic solvent may be a tertiary amine substituted with an alkyl group having 2 or more carbon atoms, more preferably a tertiary amine having 2 or more alkyl groups having 2 to 6 carbon atoms . More specifically, examples thereof include N, N-diethylacetamide, N, N-diethylformamide, N-ethylpyrrolidone, Or a mixture thereof.

The acid dianhydride that can be used in the production of the polyimide of Formula 1 may be an acid dianhydride containing the functional group X in Formula 1, for example, an intramolecular aromatic ring, a polycyclic aromatic or a combination thereof, A tetracarboxylic dianhydride containing a tetravalent organic group in which a tetravalent organic group of an aliphatic, alicyclic or aromatic group is linked to each other through a crosslinking structure.

The tetravalent organic group X of the formula (1) may be specifically selected from the group consisting of aromatic tetravalent organic groups represented by the following formulas (2a) to (2d).

 (2a)

(2b)

[Chemical Formula 2c]

(2d)

[Formula 2e]

In the above formulas (2a) to (2e), each of R ₁₁ to R ₁₇ may independently be an alkyl group having 1 to 10 carbon atoms or a fluoroalkyl group having 1 to 10 carbon atoms,

Wherein a ₁ is an integer of 0 or 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 Independently, an integer of 0 to 3, and a ₇ and a ₈ each independently may be an integer of 0 to 9, and A ₁₁ and A ₁₂ each independently represent a single bond, -O-, -CR ₁₈ R ₁₉ - , -C (= O) -, -C (= O) NH-, -S-, -SO ₂ -, phenylene and combinations thereof, wherein R ₁₈ and R ₁₉ May each independently be 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.

More specifically, X is May be, but are not limited to, tetravalent organic groups selected from the following formulas (3a) to (3n):

The aromatic tetravalent organic group of the above-mentioned formulas (3a) to (3n) is a compound wherein at least one hydrogen atom present in a tetravalent organic group is an alkyl group having 1 to 10 carbon atoms (e.g., a methyl group, an ethyl group, a propyl group, an isopropyl group, , Pentyl group, hexyl group, etc.) or a fluoroalkyl group having 1 to 10 carbon atoms (for example, a fluoromethyl group, a perfluoroethyl group, a trifluoromethyl group, etc.).

The tetracarboxylic acid dianhydride containing the above-described tetravalent organic group (X) is specifically exemplified by butanetetracarboxylic acid dianhydride, pentanetetracarboxylic acid dianhydride, hexanetetracarboxylic acid dianhydride, cyclo Cyclopentanetetracarboxylic acid dianhydride, cyclohexanetetracarboxylic acid dianhydride (PMDA-H), pyromellitic dianhydride, cyclopentanetetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride, PMDA), methylcyclohexanetetracarboxylic acid dianhydride, 3,3 ', 4,4'-benzophenonetetracarboxylic acid dianhydride, 3,4,9,10-perylenetetracarboxylic acid dianhydride, 4 , 4'-sulfonyldiphthalic dianhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic acid dianhydride, 2,3 , 6,7-naphthalenetetracarboxylic acid dianhydride, 1,4,5,8-naphthalenetetracarboxylic acid Acid dianhydride, 2,3,5,6-pyridine tetracarboxylic acid dianhydride, m-terphenyl-3,3 ', 4,4'-tetracarboxylic acid dianhydride, p- 3 ', 4,4'-tetracarboxylic dianhydride, 4,4'-oxydiphthalic dianhydride, 1,1,1,3,3,3-hexafluoro-2,2-bis [ Bis [4- (2,3- or 3,4-dicarboxyphenoxy) phenyl] propane dianhydride, and Hexafluoro-2,2-bis [4- (2,3- or 4-dicarboxyphenoxy) phenyl] propane dianhydride and the like, and particularly preferably 1,1,1,3,3,3- May be an aromatic dianhydride.

According to one embodiment, X is a tetravalent organic group derived from 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (3,3', 4,4'-biphenyltetracarboxylic dianhydride) have.

Meanwhile, the diamine compound which can be used in the production of the polyimide may be a compound containing two amino groups bonded to the Y together with the functional group Y in the formula (1).

Specifically, in Formula 1, Y is an aromatic divalent organic group derived from an aromatic diamine compound having an amino group at the para position, or a combination thereof, wherein the aliphatic, alicyclic or aromatic divalent organic group is directly connected Or may be a divalent organic group linked together through a bridging structure. More specifically, it may be selected from the group consisting of functional groups represented by the following formulas (4a) to (4d) and combinations thereof.

[Chemical Formula 4a]

(4b)

[Chemical Formula 4c]

[Chemical formula 4d]

In the above formulas (4a) to (4d)

Each of R ₅₁ to R ₅₅ independently represents an alkyl group having 1 to 10 carbon atoms (e.g., methyl, ethyl, propyl, isopropyl, t-butyl, pentyl or hexyl) An aryl group having 6 to 12 carbon atoms (e.g., a phenyl group, a naphthalenyl group, etc.), a sulfonic acid group and a carboxylic acid group (for example, a fluoroalkyl group such as a fluoromethyl group, a perfluoroethyl group and a trifluoromethyl group) Lt; / RTI > may be selected from the group consisting of < RTI ID =

A2 is an integer of 0 to 4, b2 is an integer of 0 to 6, and c2 is an integer of 0 to 3,

A ₂ is a single bond, -O-, -CR ₅₆ R ₅₇ -, -C (= O) -, -C (= O) NH-, -S-, -SO ₂ - R ₅₆ and R ₅₇ are each independently selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 10 carbon atoms (e.g., a methyl group, an ethyl group, a propyl group, an isopropyl group, a t-butyl group , A pentyl group, a hexyl group, etc.) and a fluoroalkyl group having 1 to 10 carbon atoms (e.g., a fluoromethyl group, a perfluoroethyl group, a trifluoromethyl group, etc.).

Here, when the benzene ring is included in the para position, the amino group is not limited to include the amino group at the 1,4-position, and even when the benzene ring is fused or has a structure connected to the benzene ring, Quot; means a structure in which an amino group is substituted at a remote site.

More specifically, the divalent organic group containing an amino group at the para position may be selected from the group consisting of the following formulas (5a) to (5q):

In the general formulas (5a) to (5q), A ₂ is the same as defined above, and v is an integer of 0 or 1.

In addition, at least one hydrogen atom in the divalent functional groups of the general formulas (5a) to (5q) may be an alkyl group having 1 to 10 carbon atoms (e.g., a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a pentyl group, , A fluoroalkyl group having 1 to 10 carbon atoms (e.g., a fluoromethyl group, a perfluoroethyl group or a trifluoromethyl group), an aryl group having 6 to 12 carbon atoms (e.g., a phenyl group or a naphthalenyl group) A sulfonic acid group and a carboxylic acid group.

More specifically, the diamine compound may be at least one selected from the group consisting of p-phenylenediamine, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylsulfide, 4,4'- Bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 1,3-bis (4-aminophenoxy) benzene, (4-aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy) phenyl] ] Bis (4-aminophenoxy) phenyl] ether, 4,4'-bis (4-aminophenylsulfonyl) diphenyl ether, ) Diphenyl sulfone, 1,4-bis [4- (4-aminophenoxy) benzoyl] benzene, 3,3'- - diaminodiphenylsulfone, 3,3'-diaminobenzophenone, Bis [4- (3-aminophenoxy) -phenyl] methane, 2,2-bis [4- Phenyl-1,1,1,3,3,3-hexafluoropropane, 1,3-bis (3-aminophenoxy) benzene, 4,4'-bis (3-aminophenoxy) Bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] ether, 4,4'-bis (3-aminophenylsulfonyl) diphenyl ether, 4-bis [4- (3-aminophenoxy) benzoyl] benzene, and the like, alone or in a mixture of two or more.

According to a preferred embodiment of the present invention, the Y is selected from diamines of p-phenylenediamine, 4,4'-oxydianiline, or benzidine It may be a two-gasoline appliance originating from.

The acid dianhydride and the diamine compound are preferably used in appropriate reaction ratios in consideration of the physical properties of the final polyimide. Specifically, the diamine compound may be used in an amount of about 20 to 60% by weight, preferably 20 to 50% by weight, based on 100% by weight of the acid dianhydride. If the content is out of the above range, the imidization ratio or the molecular weight of the polyimide to be produced may be lowered, and film formation may be difficult.

The polyamic acid of Formula 1 having such a structure may have a weight average molecular weight of 50,000 g / mol or more and a molecular weight distribution (Mw / Mn, PDI) of 1.4 to 1.8. If the weight average molecular weight of the polyamic acid is less than 50,000 g / mol, the high heat resistance may be deteriorated. When the molecular weight distribution of the polyamic acid is less than 1.4 or more than 1.8, there is a fear that the high heat resistance and adhesiveness may be deteriorated. Considering the effect of improving the heat resistance and adhesion of polyimide after curing of the polyimide precursor composition, the polyamic acid of Formula 1 preferably has a weight average molecular weight of 80,000 g / mol or more and a PDI (Mw / Mn) of 1.4 to 1.8 can do.

The polymerization of the acid dianhydride and the diamine compound may be carried out according to a conventional method for polymerization of a polyimide or a precursor thereof such as solution polymerization.

Specifically, when it is carried out by solution polymerization, it can be carried out by dissolving a diamine compound in the above-mentioned polymerization solvent, and then adding and reacting with an acid dianhydride. The ACD / LogP module of the ACD / Percepta platform of ACD / Labs' ACD / LogP module is used as a quantitative structure-property relationship (QSPR) ) Calculated at 25 deg. C is a positive number.

The polymerization reaction may be carried out at a temperature of less than about 10 to 30 DEG C or at a temperature of about 15 to 25 DEG C or at room temperature for about 0.5 to 5 hours or for about 1 to 3 hours, Deg.] C or at a temperature of about 40 to 60 [deg.] C for about 5 to 50 hours, or for about 10 to 40 hours, or for about 20 to 30 hours.

As a result of the polymerization reaction, polyamic acid, which is a precursor of polyimide, is produced. The polyamic acid is an acid or an acid derivative containing an -CO-NH- group and a CO-OR group (wherein R is a hydrogen atom or an alkyl group) according to the reaction of an acid anhydride group with an amino group, According to an example, there is provided a polyamic acid having the structure of Formula 6:

[Chemical Formula 6]

Wherein X and Y are the same as defined above.

The polyamic acid thus obtained as a result of the polymerization reaction is subjected to an imidation process. At this time, the imidization process may be specifically performed by a chemical imidization or thermal imidization process.

Specifically, the chemical imidization may include acid anhydrides such as acetic anhydride, propionic anhydride, benzoic anhydride, or acid chlorides thereof; A carbodiimide compound such as dicyclohexylcarbodiimide, or the like. The dehydrating agent may be used in an amount of 0.1 to 10 mol based on 1 mol of the acid dianhydride.

The chemical imidization may also be carried out at a temperature of 60 to 120 ° C.

In the case of thermal imidization, the thermal imidization may be carried out by heat treatment at a temperature of 80 to 400 ° C. At this time, a step of azeotropically removing water generated as a result of the dehydration reaction using benzene, toluene, May be more preferable.

On the other hand, the chemical or thermal imidization process may be carried out in the presence of a base catalyst such as pyridine, isoquinoline, trimethylamine, triethylamine, N, N-dimethylaminopyridine, imidazole, 1-methylpiperidine, . The base catalyst may be used in an amount of 0.1 to 5 mol based on 1 mol of the acid dianhydride.

By the imidation process, OH of -CO-NH- and OH of -CO-OH in the polyamic acid molecule are dehydrated to obtain a polyimide having the cyclic chemical structure (-CO-N-CO-) .

At this time, the polyimide of Formula 1 is obtained in a solution state dissolved in an organic solvent used in the polymerization reaction, and the solution may contain polyamic acid which is a precursor of a polyimide which is not imidized.

Accordingly, the polyimide or its precursor thus produced may be separated as a solid component and then redissolved in an organic solvent to prepare the polyimide-based solution according to the present invention, or may be used in the form of the solution obtained. The polyimide may be separated by adding a poor solvent for the polyimide such as methanol or isopropyl ether to the resultant solution to precipitate the polyimide, followed by filtration, washing, drying and the like. , And as the re-dissolving solvent, the same organic solvent as used in the above polymerization reaction may be used. That is, the ACD / LogP module of the ACD / Percepta platform of the ACD / Labs company (here, the ACD / LogP module calculates the quantitative structure-property relationship (QSPR) Lt; 0 > C and the partition coefficient (LogP value) at < 0 > C is positive can be used.

The content of the solvent may be included in an amount of the remainder, and preferably the amount is such that the polyimide precursor composition has a viscosity of 1,000 to 15,000 cp, preferably 3,000 to 8,000 cp. When the content of the organic solvent is too small and the viscosity of the polyimide precursor composition is less than 1,000 cp or the content of the organic solvent is excessively large, the content of the polyimide precursor composition exceeds 15,000 cp. In the production of the display substrate using the polyimide precursor composition There is a fear that the fairness is lowered.

The polyimide precursor composition having the above composition can provide an amorphous polyimide from the high dispersibility of the polyimide precursor. The polyimide-based film produced from the polyimide precursor composition not only exhibits high heat resistance and mechanical properties, It is possible to exhibit excellent adhesion with the glass substrate or the inorganic sacrificial layer.

The present invention also provides a method for producing a polyimide-based film comprising applying the polyimide-based solution to one surface of a substrate, curing the substrate, and separating the solution from the substrate.

Specifically, CN band appearing at 1350 to 1400cm ^-1 or 1550 to 1650cm ^-1 in the IR spectrum, applying the composition containing the polyester precursor, polyamic acid and the polyimide of the polyimide after imidization proceeds at a temperature above 450 ℃ About 60% to about 99%, or about 70% to about 98%, of the relative intensities of the CN bands after imidization at a temperature of 200 ° C or more with respect to the integral intensity of 100% And may have an imidization rate of about 75 to 96%.

The polyimide of Formula 1 may have a weight average molecular weight in terms of polystyrene of 10,000 to 200,000 g / mol, or 20,000 to 100,000 g / mol, or 40,000 to 200,000 g / mol.

The polyimide of the above formula (1) preferably has a molecular weight distribution (Mw / Mn) of 1.1 to 2.5.

If the imidization rate, the weight average molecular weight, or the molecular weight distribution of the polyimide of Formula 1 is out of the above range, film formation may be difficult or the characteristics of the polyimide-based film such as transparency, heat resistance and mechanical properties may deteriorate .

The polyimide of Formula 1 may have a glass transition temperature of about 450 캜 or higher. Since the polyimide-containing film has excellent heat resistance as described above, it can exhibit excellent heat resistance against high-temperature heat added during the device manufacturing process. Further, the polyimide-based film is used as a display substrate, It is possible to suppress the occurrence of warpage and the lowering of the reliability of other elements during the process of manufacturing the device on the substrate. As a result, it is possible to manufacture devices having improved characteristics and reliability. Therefore, the polyimide can be particularly useful for the production of a flexible substrate in an electronic device such as an OLED or an LCD, an electronic paper, or a solar cell.

On the other hand, in the production of the polyimide film using the polyimide or the precursor thereof produced according to the above-described production method, the composition for forming a polyimide film may be prepared by mixing the polyimide or a precursor thereof with an organic solvent And the organic solvent may be an organic solvent used in the polyimide-based solution.

The polyimide-based solution for forming a polyimide-based solution according to the present invention preferably contains a solid content in such an amount that the appropriate film-forming composition has an appropriate viscosity in consideration of processability such as coating properties in the film-forming step. Specifically, it may be preferable that the composition for forming a polyimide-based film is contained in an amount such that the composition has a viscosity of 1,000 to 50,000 cP. When the content of the organic solvent is too small and the viscosity of the composition for forming a polyimide film is less than 400 cP or the content of the organic solvent is excessively large and the content of the composition for forming a polyimide film exceeds 50,000 cP, There is a fear that the processability in manufacturing the display substrate using the composition is lowered. Most preferably, the solid content is 10 wt% to 25 wt%, and the viscosity may be 2,000 to 50,000 cP.

On the other hand, when the polyimide-based solution contains a precursor of polyimide, the polyamic acid-containing solution obtained as a result of the polymerization reaction of the acid dianhydride and the diamine compound in a polymerization solvent may be used.

The polyimide-based solution containing the polyimide or a precursor thereof may be generally used 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 used for forming a polyimide- As shown in FIG.

Next, a polyimide-based film is prepared by applying the above-prepared polyimide-based solution to one surface of a substrate, curing it at a temperature of 80 to 450 ° C, and then separating from the substrate.

In this case, glass, a metal substrate, a plastic substrate, or the like can be used as the substrate without any particular limitations. Among them, the substrate is excellent in heat and chemical stability during the curing process for the polyimide precursor, A glass substrate that can be easily separated without damage to the formed polyimide-based film may be desirable.

Specific examples of the coating method include a spin coating method, a bar coating method, a roll coating method, an air-knife method, a gravure method, a reverse roll method, a kiss roll method, a doctor blade method, A spray method, a dipping method, a brushing method, or the like may be used. It is more preferable to carry out the continuous process by the casting method which can increase the imidization rate of the polyimide resin.

In addition, the polyimide-based solution can be applied onto the substrate in a thickness range such that the polyimide-based film to be finally produced has a thickness suitable for a display substrate. Specifically, it may be applied in an amount such that the thickness is 10 to 20 mu m.

After the application of the polyimide-based solution, a drying process for removing the solvent present in the polyimide-based solution prior to the curing process may be further optionally performed.

The drying process may be carried out according to a conventional method. Specifically, the drying process may be performed at a temperature of 140 ° C or lower, or 80-140 ° C. If the drying temperature is lower than 80 캜, the drying process becomes longer. If the drying temperature is higher than 140 캜, the imidization rapidly proceeds to make it difficult to form a polyimide film having a uniform thickness.

Then, the curing process may be sequentially performed by heat treatment at 80 to 500 ° C or higher. The curing process may be carried out by a multi-stage heat treatment at various temperatures within the above-mentioned temperature range. In the curing step, the total curing time may be from 100 minutes to 200 minutes, and preferably from 120 minutes to 180 minutes.

If the curing time is less than 100 minutes, the adhesion between the polyimide-based film and the glass substrate and the inorganic sacrificial layer is weakened, so that the polyimide substrate may become unstable during the subsequent process, The longer the process time, the lower the production efficiency.

After the curing step, a subsequent heat treatment step may be optionally performed to increase the imidization ratio of the polyimide resin in the polyimide film to form the polyimide film having the above-mentioned physical properties.

The subsequent heat treatment is preferably performed at 200 ° C or higher, or 200 ° C to 500 ° C for 1 minute to 30 minutes. The subsequent heat treatment process may be performed once or may be performed in two or more stages. For example, three steps including a first heat treatment at 200 to 220 캜, a second heat treatment at 300 to 380 캜 and a third heat treatment at 400 to 500 캜.

Thereafter, the polyimide-based film formed on the substrate can be produced from the substrate by a conventional method to produce a polyimide-based film.

The film produced as described above may have a 1% thermal decomposition temperature (T _d1% ) of 550 ° C or higher.

The polyimide-based film may have a coefficient of thermal expansion (CTE) of about 10 ppm / ° C or less at an elevated temperature of 100 ° C to 450 ° C, and preferably a polyimide film having a high heat resistance Film.

Also, the polyimide-based film has excellent mechanical properties such as a modulus of about 5 GPa or more, about 8 GPa or more, a tensile strength of about 300 MPa or more, and an elongation of about 10 to 100%, or about 10 to 50% Based film.

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

The polyimide-based film produced by the above-described production method can exhibit high heat resistance and high mechanical strength together with a high adhesive force by including the polyimide of the formula (1). As a result, the device using the polyimide-based film can be applied to any solar cell having a flexible substrate (for example, a flexible solar cell), organic light emitting diode (OLED) lighting (for example, flexible OLED lighting) An organic electroluminescent device having a flexible substrate, an electrophoretic device, or a flexible display device such as an LCD device.

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

Distribution coefficient

First, the ACD / LogP module of the ACD / Percepta platform of ACD / Labs (where the ACD / LogP module is computed using the Quantitative Structure-Property Relationship (QSPR) methodology algorithm method using the 2D structure of the molecule) The partition coefficient (LogP value) at 0 ° C is as follows.

menstruum DEF DMF DEAc DMAc NMP NEP LogP (25 캜) 0.05 -1.01 0.32 -0.75 -0.28 0.22

In Table 1 above, the English abbreviations have the following meanings:

DMAc: N, N-Dimethylacetamide (N, N-dimethylacetamide)

DEAc: N, N-diethylacetamide (N, N-diethylacetamide)

DEF: N, N-diethylformamide (N, N-

DMF: N, N-dimethylformamide (N, N-

NMP: N-methylpyrrolidone (N-methylpyrrolidone)

NEP: N-ethylpyrrolidone (N-ethylpyrrolidone)

Example 1

14 g of 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA) were dissolved in 100 g of N, N-diethylformamide (DEF) under nitrogen atmosphere over 20 minutes. To the obtained BPDA / DEF solution, PDA / DEF solution prepared by dissolving 5.09 g of p-phenylenediamine (PDA) as a diamine compound in 33.6 g of DEF was added and reacted at 25 ° C for 24 hours, Precursor solution was prepared. The prepared polyimide precursor solution was spin coated on a glass substrate to a thickness of 20 mm. The glass substrate coated with the polyimide precursor solution was placed in an oven, heated at a rate of 6 ° C / min, and cured at a maximum temperature of 450 ° C for 160 minutes to prepare a polyimide film.

Comparative Example 1

14 g of 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA) was dissolved in 100 g of N, N-methylpyrrolidone (NMP) for 20 minutes under a nitrogen atmosphere. To the resultant BPDA / NMP solution was added PDA / NMP solution prepared by dissolving 5.09 g of p-phenylenediamine (PDA) as a diamine compound in 33.6 g of NMP, and the mixture was reacted at 25 ° C for 24 hours, Precursor solution was prepared. The prepared polyimide precursor solution was spin-coated on the glass substrate to a thickness of 20 탆. The glass substrate coated with the polyimide precursor solution was placed in an oven, heated at a rate of 6 ° C / min, and cured at a maximum temperature of 450 ° C for 160 minutes to prepare a polyimide film.

Comparative Example 2

A polyimide-based film was prepared in the same manner as in Example 1 except that N, N-dimethylacetamide (DMAc, N, N-Dimethylacetamide) was used as a solvent.

Test Example 1

The thermal expansion coefficient and thermal decomposition degree of each of the polyimide films prepared in Examples and Comparative Examples were measured in the following manner.

The thermal expansion coefficient (CTE) and 1% pyrolysis temperature of the film were measured by the method of KS M ISO 11359, and the measurement was performed by Q400 of TA. The film was prepared in the size of 5x20 mm and the sample was loaded using the accessories. The actual measured film length was equal to 16 mm. The pulling force of the film was set at 0.02 N, and the measurement starting temperature was heated to 450 占 폚 at a rate of 5 占 min at 30 占 폚, and the coefficient of linear thermal expansion of the polyimide film was measured as an average value in the range of 100 to 450 占 폚 .

The mechanical properties (tensile modulus, tensile strength, elongation) of the film were measured by the method of KS M ISO 527 using Zwick's UTM. The film was cut to a width of 5 mm or more and a length of 60 mm or more. The gap between the grips was set to 40 mm, and the sample was pulled at a speed of 20 mm / min.

Test Example 2: Evaluation of adhesion according to kinds of polymerization solvent

The polyimide films of Example 1 and Comparative Example 1 were allowed to stand at 50% humidity and 25 占 폚 for 7 days, and the adhesive strength of the film was measured.

The measurement results of Test Examples 1 and 2 are shown in Table 2. In Table 2, the English abbreviations have the following meanings:

BPDA: 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (3,3', 4,4'-biphenyltetracarboxylic dianhydride)

PDA: p-phenylenediamine (p-phenylenediamine)

DEF: N, N-diethylformamide (N, N-diethylformamide)

NMP: N-methylpyrrolidone (N-methylpyrrolidone)

DMAc: N, N-Dimethylacetamide (N, N-dimethylacetamide)

Example 1 Comparative Example 1 Comparative Example 2 Acid anhydride BPDA BPDA BPDA Diamine PDA PDA PDA menstruum DEF NMP DMAc LogP (25 캜) 0.05 -0.28 -0.75 Viscosity (cp) 7,000 7,000 7,100 thickness
(mm) 15 15 15 Adhesion (N / cm) 0.12 0.05 0.09 Tg (占 폚) 460 455 450 1% pyrolysis temperature (Td1%) 575 573 570 CTE 100 to 450 DEG C
(ppm / DEG C) 2.8 2.5 3.4 Tensile modulus (GPa)
(GPa) 9.0 9.2 8.5 Tensile Strength (MPa) 396.2 400.4 379.6 Elongation (%) 36.1 37.9 38.1

As can be seen from Table 2, the films prepared using the polyimide-based solution according to the present invention exhibited remarkable increase in adhesive strength while maintaining heat resistance and physical properties as compared with films prepared using NMP or DMAc .

While the present invention has been particularly shown and described with reference to specific embodiments thereof, those skilled in the art will appreciate that such specific embodiments are merely preferred embodiments and that the scope of the present invention is not limited thereby. something to do. It is therefore intended that the scope of the invention be defined by the claims appended hereto and their equivalents.

Claims (17)

A polyimide-based solution comprising a polyimide having a structure represented by the following formula (1) or a precursor thereof and a solvent, wherein the solvent has a distribution coefficient (LogP value) at 25 占 폚 is positive;
[Chemical Formula 1]

In Formula 1,
X is selected from the group consisting of an aromatic tetravalent organic group derived from an acid dianhydride,
And Y is an aromatic divalent organic group derived from a diamine containing an amino group at the para position. The method according to claim 1,
Wherein the solvent is a tertiary amine substituted with an alkyl group having 2 or more carbon atoms. The method according to claim 1,
Wherein the solvent is a tertiary amine having two or more alkyl groups having 2 to 6 carbon atoms. The method according to claim 1,
Wherein the solvent comprises N, N-diethylacetamide, N, N-diethylformamide, N-ethylpyrrolidone or a mixture thereof. The method according to claim 1,
Y is a polyimide-based solution which is an aromatic bifunctional apparatus derived from a diamine selected from the group consisting of the following formulas (4a) to (4d);
[Chemical Formula 4a]

(4b)

[Chemical Formula 4c]

[Chemical formula 4d]

Each of R ₅₁ to R ₅₅ independently represents an alkyl group having 1 to 10 carbon atoms, a fluoroalkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, a sulfonic acid group or a carboxylic acid group,
A2 is an integer of 0 to 4, b2 is an integer of 0 to 6, and c2 is an integer of 0 to 3,
A ₂ is a single bond, -O-, -CR ₅₆ R ₅₇ -, -C (= O) -, -C (= O) NH-, -S-, -SO ₂ - , Wherein R ₅₆ and R ₅₇ 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. The method according to claim 1,
Wherein the Y is a bifunctional apparatus derived from a diamine of p-phenylenediamine, 4,4'-oxydianiline or benzidine. The method according to claim 1,
Wherein the polyimide or polyimide precursor of Formula 1 is formed by a polymerization reaction of an acid dianhydride and a diamine, and the diamine is 20 to 60 wt% based on 100 wt% of the total acid dianhydride. The method according to claim 1,
Wherein the polyimide-based solution has a solids content of 10 wt% or more and 25 wt% or less based on the total weight of the solution. The method according to claim 1,
The polyimide precursor composition was coated on a glass substrate and cured at a temperature of 450 ° C or higher. The film thus formed was allowed to stand at 20 ° C and 50% for 1 day, and then an adhesive force of 0.2 N / cm or more was measured by the KS M ISO B510 method Wherein the film has an adhesion of 0.1 N / cm or more when measured for adhesion after being left for 7 days. 9. A method for producing a polyimide-based film, comprising applying the polyimide-based solution according to any one of claims 1 to 9 to one surface of a substrate, curing it, and then separating the polyimide-based solution from the substrate. 11. The method of claim 10,
Wherein the curing step is conducted at a temperature of 450 DEG C or higher and the total time of the curing step is 200 minutes or less. A polyimide-based film produced by the method of claim 10. 11. The method of claim 10,
Wherein the polyimide film has a 1% thermal decomposition temperature (T _d1% ) of 550 ° C or higher. 11. The method of claim 10,
Wherein the polyimide-based film exhibits a thermal expansion coefficient of 5 ppm / 占 폚 or less in the range of 100 to 450 占 폚. 11. The method of claim 10,
A polyimide film having a tensile strength of 300 MPa or more, a maximum elongation of 10% or more, and a tensile elastic modulus of 5 GPa or more. A display substrate comprising the polyimide-based film of claim 10. An element comprising a polyimide-based film according to claim 10.