KR101999918B1 - Crosslinkable Polyamic Acid Composition, and Polyimide Film Prepared by Using the Same - Google Patents

Abstract

The present invention is to provide a polyamic acid composition and a polyimide film with improved thermal resistance and mechanical properties prepared by using the same. The polyamic acid composition comprises a polyamic acid and an organic solvent and has the viscosity in the range of 1,000 to 10,000 cP. The polyamic acid is generated by polymerization of one or more types of dianhydride monomers and one or more types of diamine monomers. The dianhydride monomers comprise 1 to 10 mol% of a crosslinkable dianhydride compound based on the total content of the dianhydride monomers. The crosslinkable dianhydride compound comprises at least one triple bond in the molecular structure.

Description

Crosslinkable Polyamic Acid Composition, and Polyimide Film Prepared by Using the Same < RTI ID = 0.0 >

The present invention relates to a crosslinkable polyamic acid composition and a polyimide film produced using the same.

Polyimide (PI) is a polymer material with thermal stability based on a rigid aromatic backbone, and has mechanical properties such as excellent strength, chemical resistance, weather resistance, and heat resistance based on the chemical stability of the imide ring.

In addition, polyimide is attracting attention as a high-functional polymer material applicable to a wide range of industrial fields such as electronic, communication, and optical due to excellent electrical properties such as insulation property and low dielectric constant.

In recent years, various electronic devices have become thinner, lighter, and smaller, and research has been conducted to use a thin and lightweight polyimide film having excellent flexibility as a display substrate that can replace an insulating material of a circuit substrate or a glass substrate for a display .

In particular, in the case of a polyimide film used for a circuit board or a display substrate manufactured at a high process temperature, it is necessary to secure a higher level of dimensional stability, heat resistance and mechanical properties.

An example of a method for securing such properties is to increase the molecular weight of the polyimide.

The higher the number of imide groups in the molecule, the better the heat resistance and the mechanical properties of the polyimide film, and the longer the polymer chain, the higher the ratio of the imide groups.

In order to prepare a polyimide having a high molecular weight, the precursor polyamic acid must be prepared in a high molecular weight, but the viscosity of the polyamic acid solution also increases as the molecular weight of the polyamic acid increases.

However, when the viscosity of the polyamic acid solution is excessively high, there is a problem that the flowability is lowered and the processability is very low.

Accordingly, there is a high need for a polyimide film that simultaneously satisfies the heat resistance and mechanical properties of the polyimide film even when the viscosity of the polyamic acid composition is low.

An object of the present invention is to provide a crosslinkable polyamic acid composition and a polyimide film produced using the same.

According to one aspect of the present invention, a crosslinkable dianhydride-based compound is disclosed as an essential factor for realizing a polyimide film having excellent heat resistance and mechanical properties.

The crosslinkable dianhydride-based compound constituting the polyamic acid may form one or more crosslinks by a radical reaction between the triple bonds contained in the different polyamic acid chains during the heat treatment for imidization, The heat resistance and mechanical properties of the mid-film can be improved.

The polyimide according to the present invention has improved heat resistance and mechanical properties at the time of heat treatment for imidization, so that the viscosity of the polyamic acid composition as a precursor thereof can be kept low, and thereby the processability can be remarkably improved.

According to another aspect of the present invention, the polyimide film produced from the polyamic acid composition has a coefficient of thermal expansion (CTE) of 2.0 to 15 ppm / 占 폚, a glass transition temperature (Tg) of 360 占 폚 or more, 10% or more, a modulus of 2.7 GPa or more, and a tensile strength of 280 kgf / cm ^{2 or} more.

Such a polyimide film has an advantage of satisfying heat resistance and mechanical properties required for a display substrate.

Therefore, the present invention has a practical purpose to provide a specific embodiment thereof.

The present invention relates to a polyamic acid composition comprising a polyamic acid and an organic solvent and having a viscosity of 1,000 to 10,000 cP,

Wherein the polyamic acid is produced by polymerization of one or more dianhydride monomers and one or more diamine monomers,

Wherein the dianhydride monomer comprises 1 to 10 mol% of a crosslinkable dianhydride-based compound relative to the total content of the dianhydride monomer, wherein the crosslinkable dianhydride-based compound has at least one triple bond ≪ / RTI >

The present invention has also found that the polyimide film produced using the polyamic acid composition can realize a polyimide film having excellent heat resistance and mechanical properties even though a polyamic acid composition having a relatively low viscosity is used .

Thus, specific details for its implementation are described herein.

Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and the inventor should appropriately interpret the concepts of the terms appropriately It should be interpreted in accordance with the meaning and concept consistent with the technical idea of the present invention based on the principle that it can be defined.

Therefore, it is to be understood that the constituent features of the embodiments described herein are merely the most preferred embodiments of the present invention, and are not intended to represent all of the inventive concepts of the present invention, so that various equivalents and variations It should be understood that examples may exist.

As used herein, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. In this specification, the terms "comprising," "comprising," or "having ", and the like are intended to specify the presence of stated features, But do not preclude the presence or addition of one or more other features, integers, steps, components, or combinations thereof.

As used herein, "dianhydride" is intended to include its precursors or derivatives, which may not technically be dianhydrides, but nevertheless react with diamines to form polyamic acids And this polyamic acid can be converted back to polyimide.

As used herein, "diamine" is intended to include precursors or derivatives thereof, which, although not technically diamines, will nonetheless react with dianhydride to form a polyamic acid, / RTI >

Where an amount, concentration, or other value or parameter is given herein as an enumeration of ranges, preferred ranges, or preferred upper and lower preferred values, it is understood that any pair of any upper range limits It is to be understood that the present invention specifically discloses all ranges formed by preferred values and any lower range limits or preferred values.

Where a range of numerical values is referred to in this specification, unless otherwise stated, the range is intended to include all the integers and fractions within the endpoint and its range.

The scope of the present invention is not intended to be limited to the specific values that are mentioned when defining the scope.

First Aspect: Polyamic acid composition

The polyamic acid composition according to the present invention comprises a polyamic acid and an organic solvent and has a viscosity of 1,000 to 10,000 cP,

Wherein the polyamic acid is produced by polymerization of one or more dianhydride monomers and one or more diamine monomers,

Wherein the dianhydride monomer comprises 1 to 10 mol% of a crosslinkable dianhydride-based compound relative to the total content of the dianhydride monomer, wherein the crosslinkable dianhydride-based compound has at least one triple bond And a control unit.

The viscosity of the polyamic acid composition is in the range of 1,000 to 10,000 cP, specifically in the range of 1,000 to 8,000 cP, more specifically in the range of 1,000 to 6,000 cP.

The polyamic acid composition having such a viscosity has an advantage of being easy to handle in terms of fluidity and may be advantageous for film formation.

Specifically, when the viscosity of the polyamic acid composition is higher than the above range, when the polyamic acid composition is moved through the pipe during the polyimide manufacturing process, a higher pressure must be applied due to friction with the pipe, And the handling property may be lowered. Likewise, the higher the viscosity, the more time and expense may be required in the mixing process.

On the other hand, when the viscosity of the polyamic acid composition is below the above range, it may be difficult to obtain a desired degree of heat resistance and mechanical properties.

In addition, the crosslinkable dianhydride-based compound may be contained in an amount of 0.1 to 10 mol%, specifically 0.1 to 8 mol%, more specifically 0.1 to 5 mol%, based on the total content of the dianhydride monomer .

When the polyamic acid composition is prepared by adding a crosslinkable dianhydride compound so as to have a ratio exceeding the above range, the flexibility of the polyimide film may be lowered and the formation of the film may be difficult. In the case where the polyimide film is below the above range, The heat resistance and the mechanical properties of the polyimide film may be deteriorated.

In one specific example, the crosslinkable dianhydride-based compound may be a compound represented by the following formula (1).

(1)

(One)

Wherein L is a C2-C6 alkynyl group,

R1 and R2 each independently may be selected from the group consisting of an alkyl group, an aryl group, a carboxylic acid group, a hydroxyl group, a fluoroalkyl group and a sulfonic acid group of C1-C3,

When a plurality of R1 and R2 are present, they may be the same or different,

n and m are each independently an integer of 0 to 3;

In a more specific example, the crosslinkable dianhydride-based compound may be Ethynylbisphthalic anhydride (EBPA) represented by the following formula (2).

(2)

(2)

Herein, the triple bond contained in the molecular structure of the crosslinkable dianhydride compound is composed of three sigma (σ) bonds and two pi (π) bonds in which three electron pairs are involved in bonding, Due to the π bond, the triple bond is unsaturated and has a property of easily causing an addition reaction or a polymerization reaction and easily being cleaved.

The polyamic acid composition of the present invention contains the crosslinkable dianhydride-based compound containing the triple bond in an amount of 1 to 10 mol% based on the total amount of the dianhydride monomer. The polyamic acid composition of the present invention comprises the dianhydride monomer and the diamine monomer May comprise two or more polyamic acid chains having a triple bond derived from a cross-linkable dianhydride-based compound.

In the polyamic acid composition containing the polyamic acid chain having the above structure, since the crosslinking between the triple bonds is not formed in the solution state, the viscosity is similar to that of a conventional polyamic acid not derived from the crosslinkable dianhydride compound . However, in the heat treatment for imidization, one or more crosslinks can be formed by a radical reaction between the triple bonds contained in the different polyamic acid chains, so that after the conversion into the polyimide, The mechanical strength and heat resistance can be remarkably improved as compared with the conventional polyimide.

In a specific example, the polyamic acid comprises a first polyamic acid chain having a triple bond derived from a crosslinkable dianhydride-based compound, a second polyamic acid chain having a triple bond derived from a crosslinkable dianhydride-based compound And may be a structure including a plurality of polyamic acid chains having a triple bond in addition.

In the heat treatment for imidization, the radicals derived from the pie bonds cut in the first triple bond included in the first polyamic acid chain and the second triple bond included in the second polyamic acid chain are formed in the polyamic acid, As a form in which highly reactive radicals cross each other by a radical reaction, the first polyamic acid chain and the second polyamic acid chain can be crosslinked.

As a result, the first polyamic acid chain and the second polyamic acid chain can form crosslinks between the polyimide chains by the above-mentioned reaction in the imidization process, and in addition to the first polyamic acid chain and the second polyamic acid chain Since a plurality of polyamic acid chains each include a plurality of triple bonds, the above-mentioned crosslinking can be formed between them.

Through such cross-linking, mechanical properties and heat resistance can be remarkably improved as compared with polyimide not containing cross-linking.

According to the present invention, when a polyamic acid is produced using a crosslinkable dianhydride compound instead of preparing a polyamic acid having a very high molecular weight in order to improve the heat resistance and mechanical properties of the polyimide film, Even if a mixed acid composition is used, heat resistance and mechanical properties similar to those of a polyimide film produced from a polyamic acid having a high viscosity can be exerted. Furthermore, when a polyamic acid composition having a low viscosity is used, the processability is further improved.

On the other hand, as described above, the polyamic acid can be produced by polymerization reaction of one or more dianhydride monomers and one or more diamine monomers.

The dianhydride monomer that may be used in the preparation of the polyamic acid of the present invention may be an aromatic tetracarboxylic dianhydride.

The aromatic tetracarboxylic dianhydride may be pyromellitic dianhydride (or PMDA), 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (or BPDA), 2,3,3 ', 4'-biphenyltetracarboxylic dianhydride (or a-BPDA), oxydiphthalic dianhydride (or ODPA), diphenylsulfone-3,4,3'4'-tetracarboxylic Dianhydride (or DSDA), bis (3,4-dicarboxyphenyl) sulfide dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3,3- Hexafluoropropane dianhydride, 2,3,3 ', 4'-benzophenone tetracarboxylic dianhydride, 3,3', 4,4'-benzophenone tetracarboxylic dianhydride (or Bis (3,4-dicarboxyphenyl) propane dianhydride, p-phenylene bis (trimellitic monoester), bis Acid Anna P-biphenylene bis (trimellitic monoester acid anhydride), m-terphenyl-3,4,3 ', 4'-tetracarboxylic dianhydride, p-terphenyl- Bis (3,4-dicarboxyphenoxy) benzene dianhydride, 1,4-bis (3,4-dicarboxy Bis (3,4-dicarboxyphenoxy) phenyl] propane dianhydride, 1,4-bis (3,4-dicarboxyphenoxy) biphenyl dianhydride, 2,2- (BPADA), 2,3,6,7-naphthalenetetracarboxylic acid dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 4,4 '- (2,2-hexafluoro Diisopropylidene) diphthalic acid dianhydride, and the like. These may be used alone or in combination of two or more thereof as desired.

These dianhydride monomers may be used alone or in combination of two or more thereof as desired. However, dianhydride monomers that can be particularly preferably used in the present invention include pyromellitic dianhydride (PMDA), 3,3 ', 4,4 -Biphenyltetracarboxylic dianhydride (s-BPDA) and 2,3,3 ', 4'-biphenyltetracarboxylic dianhydride (a-BPDA). As shown in FIG.

The diamine monomers that can be used in the production of the polyamic acid of the present invention are aromatic diamines, which can be categorized as follows.

(1) A method of producing a polyimide precursor composition comprising: 1, 4-diaminobenzene (or paraphenylenediamine, PDA), 1,3-diaminobenzene, 2,4-diaminotoluene, 2,6-diaminotoluene, Diamines having one benzene nucleus structurally, such as acacia (" DABA "), etc .; diamines of relatively rigid structure;

2) diaminodiphenyl ethers such as 4,4'-diaminodiphenyl ether (or oxydianiline, ODA) and 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane (Methylenediamine), 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'- diaminobiphenyl, 2,2'-bis (trifluoromethyl ) -4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-dicarboxy-4,4'-diaminodiphenylmethane , 3,3 ', 5,5'-tetramethyl-4,4'-diaminodiphenylmethane, bis (4-aminophenyl) sulfide, 4,4'- diaminobenzanilide, Dimethylbenzidine (or o-tolidine), 2,2'-dimethylbenzidine (or m-tolidine), 3,3'-dimethoxybenzidine, 2,2'-dimethoxy Benzidine, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenylsulfide, 3,4 ' -Diaminodiphenylsulfide, 4,4'-diamino Phenyl sulfide, 3,3'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, 3,3'-diaminobenzophenone, 4,4 ' -Diaminobenzophenone, 3,3'-diamino-4,4'-dichlorobenzophenone, 3,3'-diamino-4,4'-dimethoxybenzophenone, 3,3'-diaminodiphenyl Bis (3-aminophenyl) propane, 2,2-bis (4-amino Phenyl) propane, 2,2-bis (3-aminophenyl) -1,1,1,3,3,3-hexafluoropropane, 2,2-bis , 1,3,3,3-hexafluoropropane, 3,3'-diaminodiphenylsulfoxide, 3,4'-diaminodiphenylsulfoxide, 4,4'-diaminodiphenylsulfoxide A diamine having two benzene nuclei in structure;

(3) aminophenyl) benzene, 1,4-bis (3-aminophenyl) benzene, Bis (4-aminophenoxy) benzene, 1,4-bis (3-aminophenoxy) benzene (or TPE- Benzene (or TPE-Q), 1,3-bis (3-aminophenoxy) -4-trifluoromethylbenzene, 3,3'-diamino- , 3'-diamino-4,4'-di (4-phenylphenoxy) benzophenone, 1,3-bis (3-aminophenylsulfide) benzene, Benzene, 1,4-bis (4-aminophenylsulfide) benzene, 1,3-bis (3-aminophenylsulfone) benzene, 1,3- Benzene, 1,4-bis [2- (3-aminophenyl) isopropyl] benzene, 1,4- Benzene having three structural benzene nuclei, such as bis [2- (4-aminophenyl) isopropyl] benzene, Amine;

4) bisphenols such as 3,3'-bis (3-aminophenoxy) biphenyl, 3,3'-bis (4-aminophenoxy) biphenyl, 4,4'- (4-aminophenoxy) phenyl] ether, bis [4- (aminophenoxy) phenyl] (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] ether, bis [3- (3-aminophenoxy) phenyl] ketone, bis [4- (3-aminophenoxy) phenyl] ketone, bis [4- , Bis [4- (4-aminophenoxy) phenyl] sulfide, bis [4- (3-aminophenoxy) (4-aminophenoxy) phenyl] sulfone, bis [3- (4-aminophenoxy) (3-aminophenoxy) phenyl] methane, bis [3- (4-aminophenoxy) phenyl] methane, bis [4- Phenyl] methane, bis [4- (4-aminophenoxy) phenyl] methane, 2,2-bis [3- Phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2- (BAPP), 2,2-bis [3- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 2,2- -Aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 2,2-bis [4- (3-aminophenoxy) phenyl] Such as 3,3,3-hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, Diamine with four benzene nuclei in structure.

These diamines can be used singly or in combination of two or more kinds as desired. The diamine monomers that can be particularly preferably used in the present invention include 1,4-diaminobenzene (PPD), 1,3-diaminobenzene (MPD ), 2,4-diaminotoluene, 2,6-diaminotoluene, and 3,5-diaminobenzoic acid (DABA).

When the amount of the dianhydride monomer added is less than or equal to the above range, polymerization is terminated before a desired molecular weight is reached, or a polyamic acid capable of forming a polyimide film by generating a large number of low molecular weight oligomers it's difficult.

In the polyamic acid composition, the diamine monomer and the dianhydride monomer may be substantially equimolarly charged. More specifically, the amount of the dianhydride monomer may be from 99 mol% to 101 Mol, and more specifically, the amount of the dianhydride monomer may be 99 mol% to 99.9 mol% based on 100 mol% of the diamine monomer.

When the amount of the dianhydride monomer added is less than or equal to the above range, polymerization is terminated before a desired molecular weight is reached, or a polyamic acid capable of forming a polyimide film by generating a large number of low molecular weight oligomers it's difficult.

Second aspect: Production method of polyimide film and polyimide film

The method for producing a polyimide film according to the present invention comprises:

(a) introducing at least one dianhydride monomer and at least one diamine monomer into an organic solvent and polymerizing to prepare a polyamic acid composition;

(b) drying the polyamic acid composition to form a gel film; And

(c) heat treating the gel film,

Wherein the dianhydride monomer comprises 1 to 10 mol% of a crosslinkable dianhydride-based compound relative to the total content of the dianhydride monomer, wherein the crosslinkable dianhydride-based compound has at least one triple bond . ≪ / RTI >

As described above, the polyamic acid contained in the polyamic acid composition includes at least one polyamic acid chain having a triple bond derived from a crosslinkable dianhydride compound, and in the step (c), the heat treatment for imidization , One or more crosslinks may be formed by a radical reaction between the triple bonds contained in the different polyamic acid chains.

That is, in order to increase the heat resistance and mechanical properties of the polyimide film to be produced by cross-linking between the triple bonds as described above, it is not necessary to excessively increase the molecular weight in the state of the polyamic acid composition and the polyimide film is produced from a polyamic acid having a high molecular weight Heat resistance and mechanical properties similar to those of the polyimide film can be secured.

The preparation of the polyamic acid solution in the present invention can be carried out, for example,

(1) a method in which the whole amount of the diamine monomer is put into a solvent, and then the dianhydride monomer is added so as to be substantially equimolar with the diamine monomer, and the mixture is polymerized;

(2) a method in which the whole amount of the dianhydride monomer is put into a solvent, and then, the diamine monomer is added so as to be substantially equimolar with the dianhydride monomer and polymerized;

(3) After adding some of the components of the diamine monomer into the solvent, a part of the dianhydride monomer is mixed with the reaction component in a ratio of about 95 to 105 mol%, and then the remaining components of the diamine monomer are added. A method in which a dianhydride monomer component is added to polymerize the diamine monomer and the dianhydride monomer so that they are substantially equimolar;

(4) After adding the dianhydride monomer into the solvent, the dianhydride monomer component is added to the reaction component in a proportion of 95 to 105 mol%, and then the remaining diamine monomer component To thereby polymerize the diamine monomer and the dianhydride monomer so that the diamine monomer and the dianhydride monomer are substantially equimolar;

(5) a step of reacting a part of the diamine monomer component and a part of the dianhydride monomer component in the solvent so that one of them is excessive to form the first composition, and in the other solvent, a part of the diamine monomer component and a part of the dianhydride monomer component To form a second composition, mixing the first and second compositions, and completing the polymerization, wherein when the diamine monomer component is excessive at the time of forming the first composition, the second composition , The dianhydride monomer component is excessively used, and when the dianhydride monomer component is excessive in the first composition, the diamine monomer component is excessively used in the second composition, and the first and second compositions are mixed and used So that the total diamine monomer component and the dianhydride monomer component are substantially equimolar It can be joined to the methods.

However, the polymerization method is not limited to the above examples, and any known method may be used.

The dianhydride monomer may be appropriately selected from the examples described above. Specifically, in addition to the crosslinkable dianhydride-based compound, pyromellitic dianhydride (PMDA), 3,3 ', 4,4'- At least one selected from the group consisting of biphenyltetracarboxylic dianhydride (s-BPDA) and 2,3,3 ', 4'-biphenyltetracarboxylic dianhydride (a-BPDA) .

The diamine monomer may be appropriately selected from the examples described above, and specifically, 1,4-diaminobenzene (PPD), 1,3-diaminobenzene (MPD), 2,4-diaminotoluene, 6-diaminotoluene, and 3,5-diaminobenzoic acid (DABA) may be preferably used.

In the production process of the present invention, the polyimide film can be produced through thermal imidization and the chemical imidation process can also be carried out.

The thermal imidization method is a method in which a chemical catalyst is excluded and a imidization reaction is induced by a heat source such as hot air or an infrared drier.

The thermal imidization may include the step (c), and the gel film may be heat-treated at a variable temperature ranging from 100 to 600 ° C in the step (c) Specifically, the amyl acid present in the gel film can be imidized by heat treatment at 200 to 500 ° C, more specifically 300 to 500 ° C.

However, even in the step (b) of forming the gel film, a part of the amic acid (about 0.1 to 10 mol%) may be imidized. For this, in the step (b) The polyamic acid composition can be dried at a variable temperature, and this can also be included in the category of the thermal imidation process.

The polyimide film of the present invention produced by the above production method has a CTE of 2 to 15 ppm / 占 폚, a glass transition temperature (Tg) of 360 占 폚 or more, an elongation of 10% A modulus of at least 2.7 GPa, and a tensile strength of at least 280 kgf / cm ² .

When a chemical imidization method is used in parallel, a polyimide film can be produced by using a dehydrating agent and an imidizing agent according to a method known in the art.

The present invention also provides an electronic device comprising the polyimide film, wherein the electronic device may be an electronic device including a flexible circuit board or a display substrate.

The polyamic acid composition according to the present invention includes a crosslinkable dianhydride-based compound containing at least one triple bond in the molecular structure so that, during the heat treatment for imidization, Can form one or more crosslinks by the radical reaction of the polyimide film, thereby improving the heat resistance and mechanical properties of the polyimide film.

In addition, since the polyimide according to the present invention has improved heat resistance and mechanical properties at the time of heat treatment for imidization, the viscosity of the polyamic acid composition as a precursor thereof can be kept low and the processability can be remarkably improved .

Also, the polyimide film produced from the polyamic acid composition preferably has a coefficient of thermal expansion (CTE) of 2 to 15 ppm / 占 폚, a glass transition temperature (Tg) of 360 占 폚 or more, an elongation of 10% ) Of 2.7 GPa or more and a tensile strength of 280 kgf / cm ^{2 or} more.

Such a polyimide film has an advantage of satisfying heat resistance and mechanical properties required for a display substrate.

Best Mode for Carrying Out the Invention Hereinafter, the function and effect of the present invention will be described in more detail through specific examples of the present invention. It is to be understood, however, that these embodiments are merely illustrative of the invention and are not intended to limit the scope of the invention.

The abbreviations used in Examples and Comparative Examples are as follows.

- biphenyl tetracarboxylic acid dianhydride: BPDA

- pyromellitic dianhydride: PMDA

- para-phenylenediamine: PPD

- N-methylpyrrolidone: NMP

≪ Example 1 >

Preparation Example 1: Preparation of polyamic acid composition

Agitator and nitrogen injection o 412.3 g of NMP was charged into a 500 ml reactor equipped with a discharge tube, and the temperature of the reactor was set at 30 ° C. Then, 19.2 g of PPD and 50.6 g of BPDA were added to completely dissolve and react Lt; / RTI >

After the reaction was completed, 1.44 g of BPDA was dissolved in NMP at 10 wt%, and the solution was added thereto at 10 minutes intervals until the viscosity at 23 DEG C reached 5,000 cP.

After setting the temperature of the reactor at 50 캜, 1 mole of EBPA was added per 100 moles of PPD.

The polyamic acid composition (viscosity at 23 캜: 5,500 cP) was prepared by stirring sufficiently until the reaction was completed.

Production Example 2: Preparation of polyimide film

The polyamic acid composition of Production Example 1 was subjected to high speed rotation at 1,500 rpm or more to remove bubbles.

Thereafter, the defoamed polyamic acid composition was applied to the glass substrate using a spin coater.

Thereafter, the resultant was dried in a nitrogen atmosphere at 120 ° C. for 30 minutes, heated to 450 ° C. at a rate of 2 ° C./min, heat-treated at 450 ° C. for 60 minutes, cooled to 30 ° C. at a rate of 2 ° C./min A polyimide film was obtained.

Thereafter, the polyimide film was peeled off from the glass substrate by dipping in distilled water. The thickness of the produced polyimide film was 15 탆.

The thickness of the polyimide film was measured using an electric film thickness tester manufactured by Anritsu.

≪ Example 2 >

In Production Example 1, a polyimide film was prepared in the same manner as in Example 1, except that the molar ratio of BPDA and EBPA was changed as shown in Table 1 and the viscosity of the polyamic acid composition measured was about 5,300 cP .

≪ Example 3 >

A polyimide film was produced in the same manner as in Example 1, except that PPD, BPDA, PMDA, and EBPA were added in the molar ratio shown in Table 1 instead of the monomer added in Production Example 1 and polymerization was carried out to prepare a polyamic acid composition. Respectively.

<Example 4>

A polyimide film was produced in the same manner as in Example 1, except that PPD, BPDA, PMDA, and EBPA were added in the molar ratio shown in Table 1 instead of the monomer added in Production Example 1 and polymerization was carried out to prepare a polyamic acid composition. Respectively.

&Lt; Comparative Example 1 &

In the same manner as in Example 1 except that the molar ratio of PPD and BPDA was changed as shown in the following Table 1 and the viscosity of the polyamic acid composition measured was about 5,000 cp without adding EBPA in Production Example 1 To prepare a polyimide film.

&Lt; Comparative Example 2 &

In Production Example 1, a polyimide film was prepared in the same manner as in Example 1, except that the molar ratio of BPDA and EBPA was changed as shown in Table 1 and the viscosity of the polyamic acid composition measured was about 5,200 cp .

&Lt; Comparative Example 3 &

A polyimide film was produced in the same manner as in Example 1, except that PPD, BPDA, PMDA, and EBPA were added in the molar ratio shown in Table 1 instead of the monomer added in Production Example 1 and polymerization was carried out to prepare a polyamic acid composition. Respectively.

&Lt; Comparative Example 4 &

In Production Example 1, a polyimide film was produced in the same manner as in Example 1, except that EBPA was not added and the viscosity of the measured polyamic acid composition was about 12,000 cp.

PPD
(mole%) PMDA
(mole%) BPDA
(mole%) EBPA
(mole%) Viscosity
(cP) Example 1 100 - 99 One 5,500 Example 2 100 - 95 5 5,300 Example 3 100 50 49 One 5,500 Example 4 100 50 45 5 5,300 Comparative Example 1 100 - 100 - 5,600 Comparative Example 2 100 - 89 11 5,000 Comparative Example 3 100 50 39 11 5,200 Comparative Example 4 100 - 99 One 12,000

<Experimental Example 1: Evaluation of physical properties>

The physical properties of the polyimide films prepared in Examples 1 to 4 and Comparative Examples 1, 2 and 4 were measured using the following method, and the results are shown in Table 2 below.

(1) Coefficient of thermal expansion (CTE)

Using a TA thermomechanical analyzer Q400 model, the polyimide film was cut to a width of 2 mm and a length of 10 mm. The film was stretched at a rate of 10 ° C / min under a nitrogen atmosphere at a rate of 0.05 N Lt; 0 &gt; C and then cooled at a rate of 10 [deg.] C / min.

(2) Glass transition temperature (Tg)

Dynamic mechanical analysis of a TA machine Dynamic Mechanical Analysis Using a Q800 model, the polyimide film was cut into 4 mm wide and 20 mm long, and then heated at a rate of 5 ° C / min under a nitrogen atmosphere, at a temperature of 550 ° C The glass transition temperature was measured under the conditions.

The glass transition temperature was determined as the maximum peak of tan? Calculated according to the ratio of storage modulus and loss modulus.

(3) elongation, modulus and tensile strength

The polyimide film was cut to a width of 10 mm and a length of 40 mm, and then the elongation, modulus and tensile strength were measured by an Instron5564 UTM instrument of Instron by ASTM D-882 method.

CTE
(ppm / DEG C) Tg
(° C) Elongation
(%) Modulus
(GPa) The tensile strength
(kgf / cm ² ) Example 1 7.5 367 23 8.4 373 Example 2 4.5 378 25 8.7 386 Example 3 7.2 430 13 9.0 284 Example 4 5.2 441 15 9.2 297 Comparative Example 1 15.8 337 20 8.0 277 Comparative Example 2 23.0 330 5 6.5 223 Comparative Example 4 21.7 356 22 8.3 261

Referring to Table 1, it can be confirmed that the polyimide films of Examples 1 to 4 prepared from the polyamic acid composition containing EBPA as a monomer within the scope of the present invention have excellent heat resistance at a glass transition temperature of 360 ° C or higher, , Higher than 10,000 cP, i.e., higher than the glass transition temperature of the polyimide film of Comparative Example 4 prepared from a high molecular weight polyamic acid composition.

On the other hand, in the case of the polyimide film of Comparative Example 1 prepared from the polyamic acid composition having a similar viscosity to the examples of the present invention but containing EBPA as a monomer, the CTE was out of the scope of the present invention, The transition temperature and the tensile strength are low, the dimensional stability is low, and the heat resistance and mechanical properties are not excellent.

Similarly, in the case of the polyimide film of Comparative Example 2 prepared from the polyamic acid composition prepared by adding EBPA in an excess amount, the CTE was out of the range of the present invention and the glass transition temperature was lower than those of Examples, Low heat resistance, an elongation of 10% or less, a tensile strength of 280 kgf / cm ² , It can be confirmed that the mechanical properties are lower than those of the examples.

As a result, in the case of the polyimide films of Examples 1 to 4 prepared from the polyamic acid composition which satisfied the heat treatment temperature for imidization within the scope of the present invention and into which EBPA was added to the polyamic acid within the scope of the present invention, Although the polyimide film is produced from a polyimide film composition having a low viscosity, that is, a low molecular weight polyimide film, the properties such as thermal expansion coefficient, glass transition temperature, elongation, modulus and tensile strength of the polyimide film are excellent. It can be preferably used for an electronic device including a substrate.

&Lt; Experimental Example 2: Film outer appearance evaluation &

The appearance of the polyimide films prepared in Examples 3 and 4 and Comparative Example 3 was visually observed and judged whether or not they could be used commercially. The results are shown in Table 3 below.

For example, when it is a good film, it is represented by 'O', and when it is judged to be defective by having no self-supporting property or brittleness property, it is expressed as 'X'.

Appearance evaluation Example 3 O Example 4 O Comparative Example 3 X

From the results in Table 3, it can be understood that in the case of using PPD as the diamine monomer, PMDA and BPDA as the dianhydride monomers, and in the case of Comparative Example 3 using EBPA excessively deviating from the scope of the present invention, .

Although the present invention has been fully described by way of example with reference to the accompanying drawings, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention.

Claims (16)

A polyamic acid composition comprising a polyamic acid and an organic solvent,
Viscosity ranging from 1,000 to 10,000 cP,
Wherein the polyamic acid is produced by polymerization of one or more dianhydride monomers and one or more diamine monomers,
Wherein the dianhydride monomer comprises 1 to 10 mol% of a crosslinkable dianhydride-based compound relative to the total content of the dianhydride monomer, wherein the crosslinkable dianhydride-based compound has at least one triple bond / RTI &gt;
Wherein the polyimide film produced from the polyamic acid composition has a glass transition temperature (Tg) of 360 DEG C or more and an elongation of 13% or more. The method according to claim 1,
Wherein the crosslinkable dianhydride compound is represented by the following formula (1): &lt; EMI ID =

(One)
Wherein L is a C2-C6 alkynyl group,
R1 and R2 each independently may be selected from the group consisting of an alkyl group, an aryl group, a carboxylic acid group, a hydroxyl group, a fluoroalkyl group and a sulfonic acid group of C1-C3,
When a plurality of R1 and R2 are present, they may be the same or different,
n and m are each independently an integer of 0 to 3; The method according to claim 1,
The crosslinkable dianhydride-based compound is Ethynylbisphthalic anhydride (EBPA) Polyamic acid composition. The method according to claim 1,
Wherein the polyamic acid comprises two or more polyamic acid chains having a triple bond derived from a crosslinkable dianhydride-based compound,
Wherein the polyamic acid composition forms one or more crosslinks by a radical reaction between the triple bonds contained in the different polyamic acid chains during the heat treatment for imidization. The method according to claim 1,
Wherein the dianhydride monomer is selected from the group consisting of pyromellitic dianhydride (PMDA), 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) and 2,3,3', 4 ' -Biphenyltetracarboxylic dianhydride (a-BPDA). &Lt; RTI ID = 0.0 &gt; 11. &lt; / RTI &gt; The method according to claim 1,
Wherein the diamine monomer is at least one selected from the group consisting of 1,4-diaminobenzene (PPD), 1,3-diaminobenzene (MPD), 2,4-diaminotoluene, 2,6-diaminotoluene and 3,5- (DABA). &Lt; / RTI &gt; A method for producing a polyimide film,
(a) introducing at least one dianhydride monomer and at least one diamine monomer into an organic solvent and polymerizing to prepare a polyamic acid composition;
(b) drying the polyamic acid composition to form a gel film; And
(c) heat treating the gel film,
Wherein the dianhydride monomer comprises 1 to 10 mol% of a crosslinkable dianhydride-based compound relative to the total content of the dianhydride monomer, wherein the crosslinkable dianhydride-based compound has at least one triple bond / RTI &gt;
Wherein the polyimide film has a glass transition temperature (Tg) of 360 DEG C or more and an elongation of 13% or more. 8. The method of claim 7,
The polyamic acid contained in the polyamic acid composition comprises two or more polyamic acid chains having a triple bond derived from a crosslinkable dianhydride compound,
Wherein during heat treatment for imidization, one or more crosslinks are formed by radical reactions between the triple bonds contained in the different polyamic acid chains. 8. The method of claim 7,
Wherein the crosslinkable dianhydride compound is represented by the following formula (1):

(One)
Wherein L is a C2-C6 alkynyl group,
R1 and R2 each independently may be selected from the group consisting of an alkyl group, an aryl group, a carboxylic acid group, a hydroxyl group, a fluoroalkyl group and a sulfonic acid group of C1-C3,
When a plurality of R1 and R2 are present, they may be the same or different,
n and m are each independently an integer of 0 to 3; 8. The method of claim 7,
Wherein the crosslinkable dianhydride compound is Ethynylbisphthalic anhydride (EBPA). 8. The method of claim 7,
The polyimide film is produced through thermal imidization,
Is dried at a variable temperature in the range of 50 DEG C to 200 DEG C in the step (b)
Treated at a variable temperature ranging from 100 ° C to 600 ° C in the step (c). 8. The method of claim 7,
Wherein the dianhydride monomer is selected from the group consisting of pyromellitic dianhydride (PMDA), 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) and 2,3,3', 4 ' - biphenyltetracarboxylic dianhydride (a-BPDA), wherein the at least one selected from the group consisting of:
Wherein the diamine monomer is at least one selected from the group consisting of 1,4-diaminobenzene (PPD), 1,3-diaminobenzene (MPD), 2,4-diaminotoluene, 2,6-diaminotoluene and 3,5- (DABA). &Lt; / RTI &gt; A polyimide film produced by the production method according to claim 7,
A coefficient of thermal expansion (CTE) of 2.0 to 15 ppm / 占 폚,
A modulus of at least 2.7 GPa,
A polyimide film having a tensile strength of 280 kgf / cm ² or more. 14. The method of claim 13,
Wherein the polyimide film has a thickness of 5 to 50 mu m. 14. An electronic device comprising a polyimide film according to claim 12. 16. The electronic device of claim 15, wherein the electronic device comprises a flexible circuit board or a display substrate.