TWI773889B - Polyimide precursor composition for improving adhesion property of polyimide film, polyimide film prepared therefrom and preparation method thereof, and electronic device comprising the same - Google Patents

Abstract

The present invention provides a polyimide precursor composition, a polyimide film prepared by using the same, a preparation method thereof, and an electronic device including the polyimide film. The polyimide precursor composition comprises: a polyamide acid solution, prepared by polymerizing more than one dianhydride monomer and more than one diamine monomer in an organic solvent; an aromatic carboxylic acid having 4 more than one carboxyl group; and an antioxidant; and the above-mentioned dianhydride monomer includes an adhesive dianhydride monomer represented by the following chemical formula 1, and the elongation of the polyimide film prepared from the above-mentioned polyimide precursor composition is 13% or more. In Chemical Formula 1, the definition of each substituent is the same as that in the embodiment of the specification.

Description

A polyimide precursor composition for improving the adhesion of a polyimide film, a polyimide film prepared from the above-mentioned polyimide precursor composition, a preparation method thereof, and a polyimide film comprising the same electronic device

The present invention relates to a polyimide precursor composition for improving the adhesion of a polyimide film and a polyimide film prepared from the above-mentioned polyimide precursor composition.

Polyimide (PI) is a thermally stable polymer substance based on a strong aromatic backbone, and has excellent strength, chemical resistance, and weather resistance based on the chemical stability of the imine ring. , heat resistance and other mechanical properties.

Not only that, polyimide is favored as a highly functional polymer material that can be widely used in electronics, communication, optics and other industrial fields due to its excellent electrical properties such as insulating properties and low dielectric constant.

Recently, various electronic devices have been reduced in thickness, weight, and size. Therefore, many studies have been directed to the use of thin polyimide films that are lightweight and excellent in flexibility as insulating materials that can replace circuit boards or glass substrates for displays. orientation of the display substrate.

In particular, polyimide films used for circuit substrates or display substrates prepared at high process temperatures need to ensure higher levels of dimensional stability, heat resistance, and mechanical properties.

One of the methods for securing such physical properties is a method of increasing the molecular weight of polyimide.

The reason is that the more imide groups in the molecule, the more the heat resistance and mechanical properties of the polyimide film can be improved, and the longer the polymer chain, the more the ratio of imide groups increases, so the preparation of high-molecular-weight polyimide films. Polyimide is useful for securing physical properties.

In order to prepare a high-molecular-weight polyimide, usually, after preparing a polyimide as a precursor thereof to a high molecular weight, imidization is performed by heat treatment.

However, the higher the molecular weight of the polyamic acid, the more problems arise in that the viscosity of the polyamic acid solution in which the polyamic acid is dissolved in the solvent increases, the fluidity decreases, and the processability becomes very low.

In addition, in order to maintain the molecular weight of the polyamic acid and reduce the viscosity of the polyamic acid solution, a method of reducing the solid content and increasing the solvent content can be considered, but in this case, a large amount of solvent needs to be removed during the hardening process. , so there will be problems of increased manufacturing cost and process time.

On the other hand, polyimide resins generally undergo chemical changes, ie, oxidation reactions, by light, heat, pressure, shearing force, and the like in the presence of oxygen. Such an oxidation reaction changes physical properties due to molecular chain cleavage, crosslinking, etc. in the polyimide resin, thereby causing a problem that the heat resistance and mechanical properties of the produced polyimide film are lowered.

In order to solve such a problem, a method of adding a small amount of additives such as antioxidants is used. The above-mentioned antioxidants, for example, have the effect of stabilizing the polyimide resin by removing oxygen atoms of the oxidized polyimide resin. Phosphate and sulfur compounds.

However, the commonly used antioxidants have the property of being decomposed at high temperature, especially in the preparation of polyimide resins, high temperature heat treatment is usually performed to achieve imidization, so there is an antioxidant effect at this time by decomposing the antioxidants Reduced or, as the case may be, completely incapable of exerting this effect.

On the other hand, a polyimide film is usually prepared by forming a polyimide film onto a support and drying to prepare a gel film and the above-mentioned method for imidizing the gel film to prepare a polyimide film. In the above preparation process, There is a problem in that a liquid curling phenomenon in which the gel film is rolled up or a lifting phenomenon in which a part of the gel film is peeled off from the support occurs.

That is, the polyamic acid including the dianhydride monomer and the diamine monomer has very low or almost no adhesion to the support including the inorganic substrate, so it will be produced in the above-mentioned preparation process with The problem of support body separation.

As described above, it is difficult to improve the properties required for a polyimide film, and in particular, the preparation of a polyimide film that satisfies various properties at the same time is a subject of continuous research in the related technical field.

Therefore, there is an urgent need to develop a technique that satisfies the properties required for the previously described polyimide film.

[The problem to be solved by the invention] The object of the present invention is to provide a polyimide solution that maintains a relatively low viscosity even if the solid content of the solution is high, and simultaneously satisfies the heat resistance and mechanical properties of the polyimide film prepared therefrom. The polyimide precursor composition that excellently maintains the adhesion with the support during the preparation process and the polyimide film prepared from the above-mentioned polyimide precursor composition.

According to one aspect of the present invention, it includes a polyamic acid solution prepared by polymerizing one or more dianhydride monomers and one or more diamine monomers in an organic solvent, an aromatic carboxylic acid having 4 or more carboxyl groups , and a polyimide precursor composition of an antioxidant is revealed as an essential factor for realizing a polyimide film that satisfies the above-mentioned properties. In particular, the above-mentioned dianhydride monomer can satisfy the above-mentioned characteristics by including an adhesive dianhydride monomer.

Therefore, the substantial object of the present invention is to provide specific examples of the above-mentioned polyimide precursor composition.

（1）[Means for Solving the Problems] The present invention provides a polyimide precursor composition comprising: a polyimide solution obtained by polymerizing one or more dianhydride monomers and one or more diamine monomers in an organic solvent an aromatic carboxylic acid having 4 or more carboxyl groups; and an antioxidant; and the above-mentioned dianhydride monomer includes an adhesive dianhydride monomer represented by the following chemical formula 1, prepared from the above-mentioned polyimide precursor composition The elongation of the polyimide film is more than 13%.

(1)

In the above Chemical Formula 1, X ₁ and X ₂ can be independently selected from the group consisting of C1-C3 alkyl groups, aryl groups, carboxyl groups, hydroxyl groups, fluoroalkyl groups and sulfonic acid groups, where X ₁ and X ₂ are In the case of more than one, they may be the same or different from each other, and n1 and n2 are each independently an integer of 0 to 3.

It is found that when the above-mentioned polyimide precursor composition is used, the solid content is high, and the process handling can be improved due to the relatively low viscosity, and the polyimide precursor composition prepared from the above-mentioned polyimide precursor composition. The imide film has excellent heat resistance and mechanical properties, and the breakability and yield of the polyimide film are improved.

Therefore, in this specification, the specific content for realizing the said polyimide film is demonstrated.

Before that, the terms or words used in this specification and the scope of the patent application for the invention should not be interpreted as the ordinary meaning or the meaning in the dictionary. In order to explain his own invention in the best way, the inventor should The principles of the concepts of terms can be appropriately defined and interpreted as meanings and concepts conforming to the technical idea of the present invention.

Therefore, the configuration of the embodiment described in this specification is only the best embodiment of the present invention, and does not represent all the technical ideas of the present invention. Therefore, it should be understood that from the perspective of the present application, there may be alternatives Various equivalents and modifications of the above-described embodiments.

In this specification, unless the other meaning is clearly indicated in the context, the expression of the singular includes the expression of the plural. In this specification, it should be understood that terms such as "comprising", "having" or "having" indicate the presence of implemented features, numbers, steps, constituent elements or their combinations, and do not preclude one or more other features, numbers, Possibilities or additional possibilities of steps, constituent elements, or combinations thereof.

In this specification, "dianhydride" refers to including its precursors or derivatives, which technically may not be dianhydrides, but even so, they react with diamines to form polyamides, The above-mentioned polyamic acid can be converted into polyimide again.

In this specification, "diamine" refers to those including its precursors or derivatives, which technically may not be diamines, but even so, they also react with dianhydrides to form polyamides. The above-mentioned polyamides Amino acids can be converted into polyimides again.

In this specification, when the amount, concentration, other value or parameter is listed as a range, a preferable range or a preferable upper limit value and a preferable lower limit value, it should be understood that it has nothing to do with whether the range is otherwise disclosed. Specifically disclose all ranges formed by any pair of any upper range limit or preferred value and any lower range limit or preferred value.

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

The scope of the invention is not limited to the specific values mentioned in defining the range.

the first 1 Embodiment: Polyimide Precursor Composition

（1）The polyimide precursor composition of the present invention is characterized by comprising: a polyamide acid solution prepared by polymerizing one or more dianhydride monomers and one or more diamine monomers in an organic solvent; an aromatic carboxylate acid, having 4 or more carboxyl groups; and an antioxidant; and the above-mentioned dianhydride monomer includes an adhesive dianhydride monomer represented by the following chemical formula 1, a polyimide film prepared from the above-mentioned polyimide precursor composition The elongation is more than 13%.

(1)

In the above Chemical Formula 1, X ₁ and X ₂ can be independently selected from the group consisting of C1-C3 alkyl groups, aryl groups, carboxyl groups, hydroxyl groups, fluoroalkyl groups and sulfonic acid groups, where X ₁ and X ₂ are In the case of more than one, they may be the same or different from each other, and n1 and n2 are each independently an integer of 0 to 3.

In the above Chemical Formula 1, when the substituent of the benzene ring is not particularly specified, the substituent refers to hydrogen.

The adhesive dianhydride monomer represented by the above chemical formula 1 includes a carbonyl group (C=O) as a polar functional group between two benzene rings, and this polar functional group is in the polyimide film and the support including the inorganic substrate. The subsequent reaction between the surfaces increases.

For example, the above-mentioned subsequent reaction includes the physical bonding between the polyimide film and the surface of the support, the hydrogen bonding between the polyimide film and the metalloid oxide film or the metal oxide film on the surface of the support, the polyimide film and the support. surface chemisorption, etc.

Specifically, in the present invention, the carbonyl group included in the adhesive dianhydride monomer enhances the chemical adsorption reaction through the polar functional group in the above-mentioned subsequent reaction, so that it can be used in the preparation process of the polyimide film. The liquid curling phenomenon in which the gel film rolls up or the lifting phenomenon in which a part is peeled off from the support is minimized.

In the present invention, the adhesive dianhydride monomers that can be particularly preferably used may include dianhydrides selected from the group consisting of 2,3,3',4'-benzophenone tetracarboxylic dianhydride, 3,3',4,4' - One or more of the group consisting of benzophenone tetracarboxylic dianhydride (BTDA), but not limited to this.

Next, the above-mentioned aromatic carboxylic acid may include a group selected from 3,3',4,4'-biphenyltetracarboxylic acid (3,3',4,4'-biphenyltetracarboxylic acid, BPTA), pyromellitic acid (pyromellitic acid) , PMA), 1,2,3,4-benzenetetracarboxylic acid (1,2,3,4-benzenetetracarboxylic acid), benzophenone-3,3',4,4'-tetracarboxylic acid (benzophenone-3 ,3',4,4'-tetracarboxylic acid), pyridine [well] tetracarboxylic acid (pyrazinetetracarboxylic acid), 2,3,6,7-naphthalenetetracarboxylic acid (2,3,6,7-naphthalenetetracarboxylic acid) and one or more of the group consisting of naphthalene-1,4,5,8-tetracarboxylic acid.

In the present invention, the aromatic carboxylic acid having 4 or more carboxyl groups is polymerized at a temperature in the process of polymerizing a polyamic acid solution or preparing a polyimide precursor composition, for example, at a temperature of 40°C to 90°C. polyamide acid, but then a ring-closure dehydration reaction is caused when heat treatment for imidization is performed thereafter, so that a carboxyl group can form a dianhydride group.

After the aromatic carboxyl group forms a dianhydride group, the terminal amine group of the polyamide chain or the polyimide chain reacts with the dianhydride group to form a dianhydride group, thereby increasing the length of the polymer chain.

The imide groups generated in this way can be imidized at high temperature to increase the length of the polyimide chain.

As described above, the polyimide precursor composition including the above-mentioned aromatic carboxylic acid can maintain a low viscosity, and thus can significantly improve the processability. In addition, by increasing the length of the polymer chain during the heat treatment for imidization, the mechanical properties and heat resistance can be significantly improved compared to polyimide films prepared using polyimide of similar molecular weight.

Based on the above-mentioned diamine monomer of 100 mol %, the content of the above-mentioned dianhydride monomer can be 93 mol % to 98.8 mol %, and the content of the above-mentioned adhesive dianhydride monomer is 1 mol % to 5 mol % The content of the above-mentioned aromatic carboxylic acid having 4 or more carboxyl groups is 0.2 mol % to 2 mol %.

First, when content of the said adhesive dianhydride monomer exceeds the said range, the heat resistance and mechanical property of a polyimide film will fall.

In addition, the increase in the carbonyl group included in the above-mentioned adhesive dianhydride monomer increases the hygroscopicity of the polyimide film, which causes problems such as an increase in the dielectric constant of the polyimide film.

Conversely, when the content of the adhesive dianhydride monomer is less than the above-mentioned range, the adhesive force of the desired level cannot be ensured, which is not preferable.

Next, when the content of the above-mentioned aromatic carboxylic acid is larger than the above-mentioned range, the heat resistance of the polyimide film is lowered, the flexibility is lowered, and the film appearance is defective, and when the content of the above-mentioned aromatic carboxylic acid is less than the above-mentioned range, the desired result cannot be achieved. The desired level of low viscosity is therefore not good.

On the other hand, the decomposition temperature of 5 wt % of the antioxidant may be 380° C. or higher, and specifically, the decomposition temperature of 5 wt % may be 400° C. or higher.

（2）Specifically, the above-mentioned antioxidant may include a compound represented by the following Chemical Formula 2.

(2)

In the above Chemical Formula 2, R ₁ to R ₆ can be independently selected from the group consisting of C1-C3 alkyl groups, aryl groups, carboxyl groups, hydroxyl groups, fluoroalkyl groups and sulfonic acid groups, and n is an integer from 1 to 4 , when R ₁ to R ₆ are plural, they may be the same or different from each other, and m1 to m6 are each independently an integer of 0 to 3.

In the above-mentioned Chemical Formula 2, when the substituent of the benzene ring is not particularly specified, the above-mentioned substituent refers to hydrogen.

（2-1）In a specific example, in the above Chemical Formula 2, n may be 1, and m1 to m6 are 0. In more detail, the above-mentioned antioxidant may include the compound of the following Chemical Formula 2-1.

(2-1)

This antioxidant has low volatility and excellent thermal stability, so it does not decompose or volatilize during the preparation process of the polyimide film, and can play a role in preventing the polyimide group or polyimide in the polyimide precursor composition. The effect of imine group oxidation of imine films.

Conversely, 5% by weight of the antioxidant whose decomposition temperature is 380° C. or lower is decomposed at high temperature during the production process of the polyimide film, so that the effect achieved by adding the antioxidant as described above cannot be exhibited.

The aforementioned antioxidant can be included in a range of 0.1 parts by weight to 2 parts by weight with respect to 100 parts by weight of the solid content of the polyimide precursor composition.

When the content of this antioxidant is greater than the above range, the heat resistance of the polyimide film will decrease, and deposition or blooming phenomenon will occur in the polyimide film, which will reduce the mechanical properties, and the appearance of the film. Defects will occur, so they are suboptimal.

On the contrary, when content of the said antioxidant is less than the said range, since the antioxidant effect cannot fully be exhibited, it is unfavorable.

The above-mentioned polyimide precursor composition may contain 10 to 20% by weight of solid content based on the entire weight of the above-mentioned polyimide precursor composition.

When the solid content of the above-mentioned polyimide precursor composition is greater than the above-mentioned range, the viscosity of the polyimide precursor composition will inevitably increase, so it is not good. On the contrary, in the above-mentioned polyimide precursor composition When the solid content of the material is less than the above-mentioned range, a large amount of solvent needs to be removed during the hardening process, resulting in problems of increased production cost and process time.

In addition, the viscosity of the above-mentioned polyimide precursor composition at 23° C. is in the range of 1,000 cP to 20,000 cP, in detail, in the range of 2,000 cP to 10,000 cP, more specifically in the range of 3,000 cP to 6,000 cP scope.

The polyimide precursor composition with such viscosity has the advantage of being easy to handle in the manufacturing process in terms of fluidity, and is also beneficial to the film forming. In detail, when the viscosity of the above-mentioned polyimide precursor composition is greater than the above-mentioned range, in the preparation process of the polyimide film, when the polyimide precursor composition is moved by a pipe, due to Higher pressure is required due to friction with the tube, so process cost increases and handleability decreases. In addition, the higher the viscosity, the more time and expense will be spent in the mixing process.

On the contrary, when the viscosity of the above-mentioned polyimide precursor composition is less than the above-mentioned range, since a large amount of solvent needs to be removed during the hardening process, the problems of increased preparation cost and process time will arise.

On the other hand, the above-mentioned polyimide precursor composition may further include silicone additives.

With respect to 100 parts by weight of the solid content of the above-mentioned polyimide precursor composition, 0.01 part by weight to 0.05 part by weight of silicone additives may be included.

When the content of such silicone additives is greater than the above range, the mechanical properties of the prepared polyimide film will be reduced. It is unfavorable because it decomposes at a high temperature, but rather reduces the adhesive force between the gel film and the support.

On the contrary, when the content of the above-mentioned silicone-based additive is less than the above-mentioned range, the effect of sufficiently improving the smoothness of the surface of the prepared polyimide film cannot be exhibited, which is unfavorable.

The above-mentioned silicone additives may include, for example, dimethylpolysiloxane, polyether modified polydimethylsiloxane, and polymethylalkylsiloxane. , One or more of the group consisting of silicon-based compounds including hydroxyl group (-OH) and double bond structure (C=C), but not limited to this.

In a specific example, the above-mentioned polyimide precursor composition may further include an alkoxysilane coupling agent.

Specifically, the alkoxysilane coupling agent may be included in an amount of 0.01 to 0.05 parts by weight relative to 100 parts by weight of the solid content of the polyimide precursor composition.

When the content of the alkoxysilane coupling agent is larger than the above-mentioned range, the mechanical properties will decrease, and when the heat treatment for imidization is performed, the above-mentioned alkoxysilane coupling agent will be decomposed at high temperature instead. Since the adhesive force between the gel film and the support decreases, it is not good.

On the contrary, when content of the said alkoxysilane coupling agent is less than the said range, the peeling suppression effect with respect to a support cannot fully be exhibited, and it is unfavorable.

The above-mentioned alkoxysilane coupling agent may include, for example, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldimethoxysilane, -aminopropylmethyldiethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-phenylaminopropyltrimethoxysilane, 2-aminobenzene One or more of the group consisting of trimethoxysilane and 3-aminophenyltrimethoxysilane, but not limited to this.

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

The dianhydride monomer that can be used to prepare the polyamic acid solution of the present invention may be an aromatic tetracarboxylic dianhydride.

Examples of the above-mentioned aromatic tetracarboxylic dianhydride include pyromellitic dianhydride (or PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (or s-BPDA), 2,3,3 ',4'-Biphenyltetracarboxylic dianhydride (or α-BPDA), Oxydiphthalic dianhydride (or ODPA), Diphenyl-3,4,3',4'-tetracarboxylic acid Dianhydride (or DSDA), bis(3,4-dicarboxyphenyl) thioether dianhydride, 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3 - Hexafluoropropane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, p-phenylene bis(trimellitic acid) Formic acid monoester anhydride), p-biphenyl bis (trimellitic acid monoester anhydride), m-terphenyl-3,4,3',4'-tetracarboxylic dianhydride, p-terphenyl-3, 4,3',4'-tetracarboxylic dianhydride, 1,3-bis(3,4-dicarboxyphenoxy)phthalic anhydride, 1,4-bis(3,4-dicarboxyphenoxy) Phthalic anhydride, 1,4-bis(3,4-dicarboxyphenoxy)biphthalic anhydride, 2,2-bis[(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (BPADA ), 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 4,4'-(2,2-hexafluoroisopropylidene)di Phthalic dianhydride, etc. These and the like can be used alone or in combination of two or more, as desired.

These and the like can be used alone or in combination of two or more according to need, but in the present invention, the dianhydride monomer that can be used particularly preferably can be selected from pyromellitic dianhydride (PMDA), 3,3' One or more of the group consisting of ,4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) and 2,3,3',4'-biphenyltetracarboxylic dianhydride (α-BPDA).

The diamine monomers that can be used for preparing the polyamic acid solution of the present invention can be classified and listed as aromatic diamines as follows.

1) Such as 1,4-diaminobenzene (or p-phenylenediamine, PDA), 1,3-diaminobenzene, 2,4-diaminotoluene, 2,6-diaminotoluene, 3, Diamines such as 5-diaminobenzoic acid (or DABA), which are diamines having one benzene nucleus in the structure, are relatively rigid diamines; 2) such as 4,4'-diaminodiphenyl ether (or oxydiphenylamine, ODA), 3,4'-diaminodiphenyl ether and other diamine diphenyl ethers, 4,4'-diamine Diphenylmethane (methylenediamine), 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl Benzene, 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-aminobenzene base) thioether, 4,4'-diaminobenzidine, 3,3'-dichlorobenzidine, 3,3'-dimethylbenzidine (or o-toluidine), 2,2' - Dimethylbenzidine (or m-tolidine), 3,3'-dimethoxybenzidine, 2,2'-dimethoxybenzidine, 3,3'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl bismuth, 3,4'-diaminodiphenyl bismuth, 4,4'-diaminodiphenyl bismuth, 3,3'-diaminobenzophenone, 4,4'-diaminodiphenyl Benzophenone, 3,3'-diamino-4,4'-dichlorobenzophenone, 3,3'-diamino-4,4'-dimethoxybenzophenone, 3, 3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 2,2-bis(3-aminophenyl)propane, 2,2-bis(4-aminophenyl) Propane, 2,2-bis(3-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 2,2-bis(4-aminophenyl)-1,1, 1,3,3,3-hexafluoropropane, 3,3'-diaminodiphenylene, 3,4'-diaminodiphenylene, 4,4'-diaminodiamine Diamines with 2 benzene nuclei in the structure, such as base diphenyl sulfene; 3) Such as 1,3-bis(3-aminophenyl)benzene, 1,3-bis(4-aminophenyl)benzene, 1,4-bis(3-aminophenyl)benzene, 1, 4-Bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(3-aminophenoxy)benzene (or TPE-Q) , 1,4-bis(4-aminophenoxy)benzene (or TPE-Q), 1,3-bis(3-aminophenoxy)-4-trifluoromethylbenzene, 3,3' -Diamino-4-(4-phenyl)phenoxybenzophenone, 3,3'-diamino-4,4'-bis(4-phenylphenoxy)benzophenone, 1,3-bis(3-aminophenylsulfide)benzene, 1,3-bis(4-aminophenylsulfide)benzene, 1,4-bis(4-aminophenylsulfide)benzene , 1,3-bis(3-aminophenyl)benzene, 1,3-bis(4-aminophenyl)benzene, 1,4-bis(4-aminophenyl)benzene, 1 ,3-bis[2-(4-aminophenyl)isopropyl]benzene, 1,4-bis[2-(3-aminophenyl)isopropyl]benzene, 1,4-bis[2 -(4-aminophenyl)isopropyl]benzene and other diamines having 3 benzene nuclei in the structure; 4) Such as 3,3'-bis(3-aminophenoxy)biphenyl, 3,3'-bis(4-aminophenoxy)biphenyl, 4,4'-bis(3-aminophenoxy)biphenyl phenoxy)biphenyl, 4,4'-bis(4-aminophenoxy)biphenyl, bis[3-(3-aminophenoxy)phenyl]ether, bis[3-(4- Aminophenoxy)phenyl]ether, bis[4-(3-aminophenoxy)phenyl]ether, bis[4-(4-aminophenoxy)phenyl]ether, bis[3 -(3-aminophenoxy)phenyl]ketone, bis[3-(4-aminophenoxy)phenyl]ketone, bis[4-(3-aminophenoxy)phenyl]ketone , bis[4-(4-aminophenoxy)phenyl]ketone, bis[3-(3-aminophenoxy)phenyl]sulfide, bis[3-(4-aminophenoxy) ) phenyl] sulfide, bis[4-(3-aminophenoxy)phenyl]sulfide, bis[4-(4-aminophenoxy)phenyl]sulfide, bis[3-( 3-aminophenoxy) phenyl] bis[3-(4-aminophenoxy) phenyl] bis[4-(3-aminophenoxy) phenyl] bis[4-(3-aminophenoxy) phenyl] bis [4-(4-aminophenoxy)phenyl] bis[3-(3-aminophenoxy)phenyl]methane, bis[3-(4-aminophenoxy)phenyl ]methane, bis[4-(3-aminophenoxy)phenyl]methane, bis[4-(4-aminophenoxy)phenyl]methane, 2,2-bis[3-(3- Aminophenoxy)phenyl]propane, 2,2-bis[3-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy) Phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), 2,2-bis[3-(3-aminophenoxy)phenyl] -1,1,1,3,3,3 hexafluoropropane, 2,2-bis[3-(4-aminophenoxy)phenyl]-1,1,1,3,3,3 hexafluoro Propane, 2,2-bis[4-(3-aminophenoxy)phenyl]-1,1,1,3,3,3 hexafluoropropane, 2,2-bis[4-(4-amine Diamines having four benzene nuclei in the structure, such as phenylphenoxy)phenyl]-1,1,1,3,3,3 hexafluoropropane.

These and the like can be used alone or in combination of two or more according to need, but in the present invention, the diamine monomer that can be used particularly preferably can be selected from 1,4-diaminobenzene (PPD), 1,4-diamine benzene (PPD), One or more of the group consisting of 3-diaminobenzene (MPD), 2,4-diaminotoluene, 2,6-diaminotoluene and 3,5-diaminobenzoic acid (DABA).

the first 2 Embodiment: the preparation method of polyimide film and polyimide film

（1）The method for preparing a polyimide film of the present invention is characterized by comprising: (a) a process for preparing a polyimide solution by polymerizing one or more dianhydride monomers and one or more diamine monomers in an organic solvent; ( b) The process of mixing antioxidants in the above-mentioned polyimide solution to prepare a mixture; (c) The process of mixing the above-mentioned mixture with an aromatic carboxylic acid having more than 4 carboxyl groups to prepare a polyimide precursor composition; and (d) the process of forming the above-mentioned polyimide precursor composition into a support and drying to prepare a gel film, and imidizing the above-mentioned gel film to prepare a polyimide film; and the above-mentioned two The anhydride monomer includes an adhesive dianhydride monomer represented by the following chemical formula 1, and the elongation of the polyimide film is 13% or more.

(1)

In the above Chemical Formula 1, X ₁ and X ₂ can be independently selected from the group consisting of C1-C3 alkyl groups, aryl groups, carboxyl groups, hydroxyl groups, fluoroalkyl groups and sulfonic acid groups, where X ₁ and X ₂ are In the case of more than one, they may be the same or different from each other, and n1 and n2 are each independently an integer of 0 to 3.

In the above Chemical Formula 1, when the substituent of the benzene ring is not particularly specified, the substituent refers to hydrogen.

In the present invention, the preparation of the polyamic acid solution, for example, can enumerate the following methods: (1) A method in which the entire amount of the diamine monomer is put into a solvent, and thereafter, the dianhydride monomer is added and polymerized in a manner that is substantially equimolar with the diamine monomer; (2) a method in which the entire amount of the dianhydride monomer is put into the solvent, and then the diamine monomer is added and polymerized in a manner that is substantially equimolar with the dianhydride monomer; (3) After putting a part of the components in the diamine monomer into the solvent, a part of the components in the dianhydride monomer is mixed at a ratio of about 95 mol % to 105 mol % with respect to the reaction components, and then added A method of polymerizing the remaining diamine monomer components and continuously adding the remaining dianhydride monomer components to make the diamine monomer and the dianhydride monomer substantially equimolar; (4) After putting the dianhydride monomer into the solvent, a part of the components in the diamine monomer is mixed at a ratio of 95 mol % to 105 mol % with respect to the reaction components, and then other dianhydride monomers are added components, and continue to add the remaining diamine monomer components to make the diamine monomer and the dianhydride monomer substantially become equimolar to carry out the polymerization method; (5) A part of the diamine monomer component and a part of the dianhydride monomer component are reacted in a solvent to form a first composition, and a part of the diamine monomer component and a part of the dianhydride monomer are used Any one of the components is reacted in another solvent to form a second composition, and then the first composition and the second composition are mixed to complete the polymerization. In this case, when the first composition is formed, the second composition is formed. When the amine monomer component is too much, the dianhydride monomer component is excessive in the second composition, and when the dianhydride monomer component is too much in the first composition, the diamine monomer component is excessive in the second composition A method in which the first composition and the second composition are mixed in such a manner that the entire diamine monomer component and the dianhydride monomer component used for the reaction are substantially equimolar and polymerized.

The above-mentioned organic solvent is not particularly limited as long as it is a solvent capable of dissolving polyamic acid, but may be an aprotic polar solvent (aprotic polar solvent) as an example.

Non-limiting examples of the aprotic polar solvent include amide-based solvents such as N,N'-dimethylformamide (DMF), N,N'-dimethylacetamide (DMAc), Phenolic solvents such as p-chlorophenol and o-chlorophenol, N-methyl-pyrrolidone (NMP), γ-butyrolactone (GBL) and diethylene glycol dimethyl ether (Diglyme), etc., which can be used alone Or use in combination of two or more.

Depending on the situation, auxiliary solvents such as toluene, tetrahydrofuran, acetone, methyl ethyl ketone, methanol, ethanol, and water can also be used to adjust the solubility of polyamic acid.

In one example, the organic solvent that can be particularly preferably used for preparing the polyimide precursor composition of the present invention can be N,N'-dimethylformamide and N,N'- Dimethylacetamide.

The above-mentioned polymerization method is not limited to the above-mentioned examples, and it goes without saying that any known method can be used.

The above-mentioned dianhydride monomers can be appropriately selected from the examples described above, and more specifically, can further include those selected from pyromellitic dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic acid One or more of the group consisting of dianhydride (s-BPDA) and 2,3,3',4'-biphenyltetracarboxylic dianhydride (α-BPDA).

The above-mentioned diamine monomer can be appropriately selected from the examples described above, and in detail, 1,4-diaminobenzene (PPD) and 1,3-diaminobenzene (MPD) can be preferably used. , one or more of the group consisting of 2,4-diaminotoluene, 2,6-diaminotoluene and 3,5-diaminobenzoic acid (DABA).

The above-mentioned process (a) can be performed at 30°C to 80°C, and the viscosity of the above polyamic acid solution at 23°C is 1,000 cP to 20,000 cP.

In addition, the above process (b) can be further mixed with an alkoxysilane coupling agent in the silicone additive and polyamic acid solution, and performed at 40°C to 90°C, and the above process (c) is performed at 40°C to 90°C The above-mentioned process (d) is carried out by the following process: the polyimide precursor composition formed on the above-mentioned support is dried at a temperature of 20 ° C to 120 ° C for 5 minutes to 60 minutes to prepare a gel film , the above gel film is heated to 450°C to 500°C at a rate of 1°C/min to 8°C/min, heat treatment is performed at 450°C to 500°C for 30 minutes to 60 minutes, at a rate of 1°C/min to 8°C Cool to 20°C to 120°C at a rate of /min.

The above-mentioned support can be, for example, an inorganic substrate. Examples of the inorganic substrate include glass substrates and metal substrates, but glass substrates are preferably used. The glass substrates can use soda lime glass, borosilicate glass, alkali-free glass, etc., but not Only limited to this.

On the other hand, in the state of the gel film, it is difficult to directly measure the adhesive force between the gel film and the support. Therefore, the adhesive force between the polyimide film prepared from the above-mentioned gel film and the support can be measured. The adhesion between the gel film and the support was assessed indirectly. The reason for this is that it is presumed that the polyimide film prepared from the above-mentioned gel film exhibits similar properties in terms of adhesion to the support.

Specifically, the adhesive force between the polyimide film and the support may be 0.3 N/cm or more, specifically, 0.5 N/cm to 1 N/cm.

That is, by including the adhesive dianhydride monomer in the above-mentioned process (a), the adhesive force between the above-mentioned gel film and the support in the above-mentioned process (d) is improved, and the liquid that can roll up the gel film The phenomenon of curling or lift-off of a portion of the peel from the support is minimized.

In addition, the aromatic carboxylic acid contained in the above-mentioned polyimide precursor composition is not polymerized into polyimide in the above-mentioned process (c), but the polyimide is subsequently subjected to heat treatment for imidization. The length of the imine chain increases, so in the process of forming the above-mentioned polyimide precursor composition into a film, the processability is good due to the low viscosity, and the length of the polymer chain increases in the subsequent curing process, so it can be Similar levels of heat resistance and mechanical properties to polyimide films prepared from polyamides with higher molecular weights.

In the preparation method of the present invention, the thermal imidization method can be used to prepare the polyimide film, and the chemical imidization method can also be used in parallel.

The above-mentioned thermal imidization method refers to a method in which an imidization reaction is induced using a heat source such as hot air or an infrared dryer while removing a chemical catalyst.

The above-mentioned thermal imidization method may be included in the above-mentioned process (d), and in the above-mentioned process (d), the above-mentioned gel film may be heat-treated at a variable temperature in the range of 100° C. to 600° C. The amide imidization of the gel film, in detail, can be heat-treated at 200°C to 500°C, more specifically at 450°C to 500°C, and the amide acid group present in the gel film can be imidized. Amination.

However, in the process of forming the above-mentioned gel film, a part (about 0.1 mol % to 10 mol %) of the amide can also be imidized. Therefore, in the process of forming the above-mentioned gel film, The polyimide precursor composition can be dried at a variable temperature in the range of 50°C to 200°C, which is also included in the scope of the thermal imidization method described above.

The coefficient of thermal expansion (CTE) of the polyimide film of the present invention prepared according to the preparation method as described above can be 1 ppm/°C to 25 ppm/°C, the elongation is 13% or more, and the thermal decomposition temperature of 1 wt% is 555°C to 620°C, glass transition temperature of 380°C or more, modulus of 8 GPa or more, tensile strength of 280 MPa or more, and thickness of 10 μm to 20 μm.

In the case of a parallel chemical imidization method, a polyimide film can be prepared using a dehydrating agent and an imidizing agent according to a method known in the industry.

The present invention can also provide an electronic device including the above-mentioned polyimide film.

[Inventive effect] The polyimide precursor composition of the present invention includes an adhesive dianhydride monomer, whereby the polyimide precursor composition is formed into a film on a support and dried to prepare a gel film and the above gel film In the process of imidization, the adhesive force between the gel film and the support can be improved to improve the production yield.

In addition, the aromatic carboxylic acid with more than 4 carboxyl groups included in the polyimide precursor composition has good process handling due to its low viscosity, and the length of the polymer chain increases during the curing process after film formation, so it can be A similar level of heat resistance and mechanical properties to polyimide films prepared from polyimide films having higher molecular weights is ensured.

In addition, 5% by weight of antioxidants with a decomposition temperature of 380°C or higher included in the polyimide precursor composition have low volatility and excellent thermal stability, so they do not decompose during the preparation process of the polyimide film Or volatilization, can prevent the amide group in the polyimide precursor composition or the amide group in the polyimide film from being oxidized, thereby minimizing the change in the physical properties of the polyimide film.

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

Hereinafter, the action and effect of the invention will be described in more detail with reference to specific embodiments of the invention. However, these embodiments are merely examples of the invention, and the right scope of the invention is not thereby defined.

Hereinafter, the compound names of the abbreviations used in Examples and Comparative Examples are as follows. - Biphenyltetracarboxylic dianhydride: BPDA - Pyromellitic dianhydride: PMDA - Biphenyltetracarboxylic acid: BPTA - p-phenylenediamine: p-PDA -N-Methylpyrrolidone: NMP

<Example 1>

Nitrogen was injected into a 500 ml reactor equipped with a stirrer and a nitrogen injection/exhaust pipe, NMP was charged, the temperature of the reactor was set to 30°C, and p-PDA as a diamine monomer and p-PDA as a dianhydride monomer were charged It was confirmed that the BPDA and BTDA as an adhesive dianhydride monomer were completely dissolved. The temperature was raised to 40°C for heating under a nitrogen atmosphere, and after stirring for 120 minutes, a polyamic acid solution with a viscosity of 6100 cP at 23°C was prepared.

（2-1）After the temperature of the reactor was set to 50°C, BYK-378 as a silicone-based additive and 5% by weight of an antioxidant were added to the polyamic acid solution at a weight ratio of 1:50:1 at a decomposition temperature of 5% by weight. The compound of the above-mentioned chemical formula 2-1 and OFS-6011 as an alkoxysilane coupling agent at about 402°C were slowly stirred for 30 minutes to prepare a silicone-based additive, an antioxidant and an alkoxysilane coupling agent. mixture.

(2-1)

After the temperature of the reactor was set to 50°C, 0.5 mol of BPTA was added to the above-mentioned mixed solution with respect to 100 mol of p-PDA. Fully stirred until the reaction was completed, NMP was added so that the total solid content was about 15% by weight and the viscosity was about 5,100 cP, and a diamine monomer, a dianhydride monomer, an aromatic carboxylic acid, and an adhesive dianhydride were prepared. The molar ratio of the monomers is 100:98.5:0.5:1, and relative to 100 parts by weight of solid content, it includes 0.01 part by weight of silicone additive, 0.5 part by weight of antioxidant, 0.01 part by weight of alkoxysilane A mixture of polyimide precursor compositions.

The bubbles of the above-mentioned polyimide precursor composition are removed by high-speed rotation of 1,500 rpm or more. Thereafter, the defoamed polyimide precursor composition was applied to the glass substrate using a spin coater. Thereafter, a gel film was prepared by drying at a temperature of 120° C. for 30 minutes in a nitrogen atmosphere, and the gel film was heated to 450° C. at a rate of 2° C./min. The polyimide film was obtained by cooling to 30°C at a rate of °C/min.

After that, the polyimide film was peeled off from the glass substrate by dipping in distilled water. The thickness of the prepared polyimide film was 15 μm. The thickness of the prepared polyimide film was measured using an Anritsu company's film thickness tester.

<Example 2 to Example 11, Comparative Example 1 to Comparative Example 12, and Comparative Example 15 to Comparative Example 19>

A polyimide film was prepared by the same method as in Example 1, except that the monomers, additives, and the viscosity of the polyimide precursor composition in Example 1 were changed as shown in Table 1 below.

<Comparative Example 13>

（A）It was prepared by the same method as in Example 1, except that 5% by weight of the compound of the following chemical formula A having a decomposition temperature of about 377°C was put in place of the compound of chemical formula 2-1 in Example 1 as an antioxidant Polyimide film.

(A)

<Comparative Example 14>

（B）Prepared by the same method as in Example 1, except that 5% by weight of the compound of the following chemical formula B having a decomposition temperature of about 338°C was put in place of the compound of the chemical formula 2-1 in Example 1 as an antioxidant Polyimide film.

(B)

[Table 1]

<Experimental Example 1: Evaluation of Adhesion>

The polyimide films prepared in Examples 1 to 11 and Comparative Examples 1 to 19 were measured for adhesion to glass substrates using a tensile tester (Instron 5564), and the results are shown in Table 2 below. .

Specifically, the polyimide film obtained in the examples was cut into a width of 10 mm with a cutter before peeling the polyimide film from the glass substrate, and measured at 23°C and 55% relative humidity ( The average value of 180-degree peel strength when peeling 50 mm at a tensile speed of 50 m/min under Relative Humidity, RH).

<Experimental Example 2: Evaluation of Physical Properties>

The physical properties of the polyimide films prepared in Examples 1 to 11 and Comparative Examples 1 to 19 were measured in the following manner, and the results are shown in Table 2 below.

(1) Coefficient of Thermal Expansion (CTE)

Using the thermomechanical analyzer (thermomechanical analyzer) Q400 model of TA company, after cutting the polyimide film with a width of 2 mm and a length of 10 mm, a tension of 0.05 N was applied in a nitrogen atmosphere, and a tension of 10 °C/min was applied. The rate was raised from normal temperature to 500°C, and then cooled again at a rate of 10°C/min to measure the inclination in the range of 100°C to 350°C.

(2) Elongation

After cutting the polyimide film with a width of 10 mm and a length of 40 mm, it was tested by the American Society for Testing and Materials using the Instron5564 universal testing machine (UTM) equipment of Instron Company. for Testing Materials, ASTM) D-882 method to determine elongation.

(3) 1 wt% thermal decomposition temperature (TD)

The polyimide membrane was heated to 150° C. at a rate of 10° C./min in a nitrogen atmosphere using a thermogravimetric analyzer Q50 from TA, and then kept isothermally for 30 minutes to remove moisture. Thereafter, the temperature was raised to 600°C at a rate of 10°C/min, and the temperature at which a 1% weight loss occurred was measured.

(4) Glass transition temperature (Tg)

Using TA's Dynamic Mechanical Analyzer (Dynamic Mechanical Analyzer) Q800 model, the polyimide film was cut with a width of 4 mm and a length of 20 mm. The glass transition temperature was measured at a heating rate of 5°C/min. The above glass transition temperature is determined as the maximum peak value of tanδ calculated from the ratio of storage modulus to loss modulus.

(5) Modulus and tensile strength

After the polyimide film was cut with a width of 10 mm and a length of 40 mm, the modulus and tensile strength were determined by the ASTM D-882 method using an Instron 5564 UTM apparatus from Instron Corporation. The cross head speed (Cross Head Speed) at this time was measured under the condition of 5 mm/min.

[Table 2]

Referring to Table 2, it was confirmed that the Examples satisfying the scope of the present invention were excellent in adhesive force, heat resistance, and mechanical properties. On the contrary, it was confirmed that the comparative example which deviates from the scope of the present invention cannot satisfy at least one of adhesive force, heat resistance, and mechanical properties.

The embodiments of the present invention have been described above, but those skilled in the technical field to which the present invention pertains can perform various applications and modifications within the scope of the present invention based on the above.

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Claims (19)

A polyimide precursor composition, comprising: a polyimide solution prepared by polymerizing more than one dianhydride monomer and more than one diamine monomer in an organic solvent; an aromatic carboxylic acid having 4 more than one carboxyl group; and 0.1 to 2 parts by weight of an antioxidant represented by the following Chemical Formula 2 relative to 100 parts by weight of the solid content of the polyimide precursor composition; and the dianhydride monomer Including the adhesive dianhydride monomer represented by the following chemical formula 1, the elongation of the polyimide film prepared from the polyimide precursor composition is 13% or more, and the glass of the polyimide film The transfer temperature is 380°C or greater, wherein the elongation is determined by the American Society for Testing and Materials (ASTM) method D-882:

In the chemical formula 1, X ₁ and X ₂ are independently selected from the group consisting of a C1-C3 alkyl group, an aryl group, a carboxyl group, a hydroxyl group, a fluoroalkyl group and a sulfonic acid group, and X ₁ and X ₂ are In multiple cases, they are the same or different from each other, and n1 and n2 are independently integers from 0 to 3:

In the chemical formula 2, R ₁ to R ₆ are independently selected from the group consisting of a C1-C3 alkyl group, an aryl group, a carboxyl group, a hydroxyl group, a fluoroalkyl group and a sulfonic acid group, and n is an integer from 1 to 4 , when R ₁ to R ₆ are plural, they are the same or different from each other, and m1 to m6 are each independently an integer of 0 to 3. The polyimide precursor composition according to item 1 of the claimed scope, wherein the adhesive dianhydride monomer comprises a dianhydride selected from the group consisting of 2,3,3',4'-benzophenone tetracarboxylic acid and 3,3',4,4'-benzophenone tetracarboxylic dianhydride, one or more of the group consisting of. The polyimide precursor composition according to item 1 of the claimed scope, wherein the aromatic carboxylic acid comprises a compound selected from the group consisting of 3,3',4,4'-biphenyltetracarboxylic acid, pyromellitic acid, 1,2,3,4-benzenetetracarboxylic acid, benzophenone-3,3',4,4'-tetracarboxylic acid, pyridine [well] tetracarboxylic acid, 2,3,6,7-naphthalenetetra One or more of the group consisting of carboxylic acid and naphthalene-1,4,5,8-tetracarboxylic acid. The polyimide precursor composition according to item 1 of the claimed scope, wherein based on 100 mol % of the diamine monomer, the content of the dianhydride monomer is 93 mol % to 98.8 mol % mol %, the content of the adhesive dianhydride monomer is 1 mol % to 5 mol %, and the content of the aromatic carboxylic acid having 4 or more carboxyl groups is 0.2 mol % to 2 mol % . The polyimide precursor composition according to claim 1, wherein the decomposition temperature of 5 wt % of the antioxidant is 380° C. or higher. The polyimide precursor composition according to claim 5, wherein the decomposition temperature of 5 wt % of the antioxidant is 400° C. or higher. The polyimide precursor composition according to claim 1, wherein in the chemical formula 2, n is 1, and m1 to m6 are 0. The polyimide precursor composition as described in item 1 of the claimed scope further comprises silicone additives. The polyimide precursor composition according to item 8 of the patent application scope, wherein relative to 100 parts by weight of the solid content of the polyimide precursor composition, it includes 0.01 part by weight to 0.05 part by weight of the Silicone additives. The polyimide precursor composition according to item 9 of the claimed scope, wherein the silicone-based additive comprises a compound selected from the group consisting of dimethylpolysiloxane, polyether-modified polydimethylsiloxane, One or more of the group consisting of polymethylalkylsiloxane and silicon-based compounds including hydroxyl and carbon-carbon double bond structures. The polyimide precursor composition as described in item 1 of the claimed scope further comprises an alkoxysilane coupling agent. The polyimide precursor composition according to item 11 of the claimed scope, wherein relative to 100 parts by weight of the solid content of the polyimide precursor composition, it includes 0.01 part by weight to 0.05 part by weight of the Alkoxysilane coupling agent. The polyimide precursor composition of claim 11, wherein the alkoxysilane coupling agent comprises selected from 3-aminopropyltrimethoxysilane, 3-aminopropyltriethyl Oxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane , one or more of the group consisting of 3-phenylaminopropyltrimethoxysilane, 2-aminophenyltrimethoxysilane, and 3-aminophenyltrimethoxysilane. A polyimide film prepared from the polyimide precursor composition described in any one of items 1 to 13 of the patent application scope. The polyimide film as described in item 14 of the scope of the application, having a thermal decomposition temperature of 555° C. to 620° C. for 1 wt %, a modulus of 8 GPa or more, a tensile strength of 280 MPa or more, and a thermal expansion coefficient of 1 ppm/° C. up to 25ppm/°C, with a thickness of 10μm to 20μm. A method for preparing a polyimide film, comprising: (a) a process for preparing a polyimide solution by polymerizing more than one dianhydride monomer and more than one diamine monomer in an organic solvent; The process of preparing a mixture by mixing the antioxidant represented by the following chemical formula 2 in the polyimide solution, wherein relative to 100 parts by weight of the solid content of the polyimide precursor composition, including 0.1 parts by weight to 2 parts by weight (c) a process for preparing a polyimide precursor composition by mixing the mixture with an aromatic carboxylic acid having more than 4 carboxyl groups; and (d) mixing the polyimide precursor The process of preparing a polyimide film by forming a film from the composition to a support and drying it to prepare a gel film, and imidizing the gel film to prepare a polyimide film, wherein the glass transition temperature of the polyimide film is 380°C or more; and the dianhydride monomer includes an adhesive dianhydride monomer represented by the following chemical formula 1, the elongation of the polyimide film is 13% or more, wherein the elongation is Determined by the American Society for Testing and Materials (ASTM) method D-882:

In the chemical formula 1, X ₁ and X ₂ are independently selected from the group consisting of a C1-C3 alkyl group, an aryl group, a carboxyl group, a hydroxyl group, a fluoroalkyl group and a sulfonic acid group, and X ₁ and X ₂ are In multiple cases, they are the same or different from each other, and n1 and n2 are independently integers from 0 to 3:

In the chemical formula 2, R ₁ to R ₆ are independently selected from the group consisting of a C1-C3 alkyl group, an aryl group, a carboxyl group, a hydroxyl group, a fluoroalkyl group and a sulfonic acid group, and n is an integer from 1 to 4 , when R ₁ to R ₆ are plural, they are the same or different from each other, and m1 to m6 are each independently an integer of 0 to 3. The method for preparing a polyimide film according to item 16 of the claimed scope, wherein the process (b) comprises further mixing silicone additives and alkoxysilane coupling agents in the polyimide solution the process of. The method for preparing a polyimide film as described in item 16 of the patent application scope, wherein the adhesive force between the polyimide film and the support is 0.3 N/cm above. An electronic device comprising the polyimide film as described in item 14 of the patent application scope.