TWI758507B - Polyimide precursor composition, preparation method thereof and polyimide substrate prepared from the composition - Google Patents

Abstract

The present invention relates to a polyimide precursor composition, a process for preparing the same, and a polyimide substrate prepared therefrom. The polyimide precursor composition has a high solids content and a low viscosity, which is advantageous for preparing a substrate and excellent in storage stability at room temperature. In addition, the polyimide substrate is excellent in heat resistance and mechanical properties so that it is suitable for use as a display substrate.

Description

Polyimide precursor composition, its preparation method and polyimide substrate prepared from the composition

FIELD OF THE INVENTION The present invention relates to a polyimide precursor composition, a preparation method thereof, and a polyimide substrate prepared from the composition. The polyimide precursor composition has high solid content and low viscosity, which is favorable for preparing substrates, and has excellent storage stability at room temperature. In addition, the polyimide substrate is excellent in heat resistance and mechanical properties, making it suitable for use as a display substrate.

BACKGROUND OF THE INVENTION In general, polyimide (PI) resin means a highly heat-resistant resin prepared by polymerizing an aromatic dianhydride with an aromatic diamine or an aromatic diisocyanate act to produce a polyamide derivative, and then the polyamide derivative undergoes ring closure and dehydration at high temperature to imidize. In addition, a polyimide resin is a highly heat-resistant resin that is insoluble and infusible. Because of its excellent properties in thermal oxidation resistance, heat resistance, radiation resistance, low temperature properties, and chemical resistance, it has been widely used in various industries, for example, as a High-order heat-resistant materials in the solar field, and electronic materials as insulating coatings, dielectric films, and electrode protection films for semiconductors and TFT-LCDs (see Korean Patent No. 1472920).

In recent years, polyimide substrates excellent in optical, mechanical, and thermal properties have been developed by a convenient method of making films of polyimide resins (ie, a polyimide precursor composition). It has been known that when a polyimide precursor composition is prepared, if the molar ratio of an aromatic dianhydride and an aromatic amine is close to 1:1, the polyimide precursor composition has a The molecular weight will increase, and the substrates prepared therefrom through thermochemical imidization have better physical properties than those described above where the molar ratio deviates from 1:1. However, the higher the molecular weight of a polyimide precursor and the higher the solids content therein, the higher the viscosity of the polyimide precursor composition, which makes it more difficult to manipulate the polyimide precursor composition and the substrates are prepared therefrom. In addition, the polyimide precursor composition with high viscosity has low storage stability at room temperature. If the polyimide precursor has a low molecular weight, the heat resistance and mechanical properties of the polyimide substrate prepared from the polyimide precursor may be insufficient. Furthermore, if a polyimide precursor composition contains a low solids content, it raises a problem that a large amount of solvent needs to be removed from the prepared substrate, and manufacturing cost and time may increase.

Summary of Invention Technical Problem

Therefore, an object of the present invention is to provide a polyimide precursor composition with high solid content, low viscosity and excellent storage stability at room temperature.

Furthermore, another object of the present invention is to provide a polyimide substrate which is excellent in heat resistance and mechanical properties, making the polyimide substrate suitable for use as a display substrate. solution to the problem

In order to achieve the above object, a polyimide precursor composition is provided, comprising: a polyamide solution prepared from a polyamide composition, the polyamide composition comprising an aromatic Dianhydride and an aromatic diamine, the aromatic dianhydride comprising 3,4,3',4'-biphenyltetracarboxylic dianhydride (BPDA), the aromatic diamine comprising p-phenylenediamine (PPD); an aromatic carboxylic acid having at least four carboxyl groups; a tertiary amine curing agent; and an antioxidant.

To achieve other objects, a polyimide substrate is provided herein, which is prepared by applying, drying, and curing the polyimide precursor composition.

Furthermore, in order to achieve other objects, there is provided a method for preparing a polyimide precursor composition, comprising: (1) mixing and reacting an aromatic dianhydride and an aromatic diamine to Prepare a polyamic acid solution, the aromatic dianhydride comprises 3,4,3',4'-biphenyltetracarboxylic dianhydride (BPDA), and the aromatic diamine comprises p-phenylenediamine (PPD); ( 2) mixing the polyamic acid solution, a tertiary amine curing agent, and an antioxidant to prepare a mixture; and (3) mixing the mixture with an aromatic carboxylic acid having at least four carboxyl groups. Utility of the present invention

The polyimide precursor composition according to the present invention has high solid content and low viscosity and is excellent in storage stability at room temperature. In addition, the polyimide substrate made from the composition is suitable for adhering to a glass or an inorganic layer in a heat treatment step of a method for manufacturing a display, and is stable in conditions such as heat resistance and thermal dimensional stability The mechanical properties are excellent.

Best Practices for Carrying Out the Invention The inventive polyimide precursor composition comprises a polyamide solution prepared from a polyamide composition comprising an aromatic diamide anhydride and an aromatic diamine, the aromatic dianhydride comprising 3,4,3',4'-biphenyltetracarboxylic dianhydride (BPDA), the aromatic diamine comprising p-phenylenediamine (PPD); a an aromatic carboxylic acid having at least four carboxyl groups; a tertiary amine curing agent; and an antioxidant. Polyamide solution

The polyamic acid solution is prepared from a polyamic acid composition comprising an aromatic dianhydride and an aromatic diamine, the aromatic dianhydride comprising 3,4,3' ,4'-biphenyltetracarboxylic dianhydride (BPDA), the aromatic diamine includes p-phenylenediamine (PPD).

The aromatic dianhydride includes 3,4,3',4'-biphenyltetracarboxylic dianhydride (BPDA).

In addition, the aromatic dianhydride may further comprise at least one aromatic dianhydride selected from the group consisting of: pyrometic acid dianhydride (PMDA), 3,3',4,4'-dianhydride Phenyl ketone tetracarboxylic dianhydride (BTDA), 2,3,3',4'-biphenyltetracarboxylic dianhydride, 1H,3H-naphtho[2,3-c:6,7-c'] Difuran-1,3,6,8-tetraone, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 4,4'-oxygen Diphthalic anhydride, 4,4'-oxybis(2-benzofuran-1,3-dione), 4-[(1,3-dioxo-1,3-dihydro-2-benzene furan-5-yl)oxy]-2-benzofuran-1,3-dione, and 5,5'-sulfonylbis-1,3-isobenzofurandione.

Specifically, the aromatic dianhydride may comprise 3,4,3',4'-biphenyltetracarboxylic dianhydride (BPDA), or it may comprise 3,4,3',4'-biphenyltetracarboxylic acid Dianhydride (BPDA) and pyromite dianhydride (PMDA). In addition, the aromatic dianhydride may comprise 3,4,3',4'-biphenyltetracarboxylic dianhydride (BPDA) and 3,3',4,4'-diphenylketone tetracarboxylic dianhydride ( BTDA), or it may contain 3,4,3',4'-biphenyltetracarboxylic dianhydride (BPDA), pyromite dianhydride (PMDA), and 3,3',4,4'-diphenyl dianhydride Phenyl ketone tetracarboxylic dianhydride (BTDA).

The polyamic acid composition may contain 0.1 to 70 moles of additional aromatic dianhydride per 100 moles of aromatic diamine. Specifically, the polyamic acid composition may contain 2 to 65 moles of additional aromatic dianhydride per 100 moles of aromatic diamine. More specifically, the polyamic acid composition may comprise 42 to 99 moles of BPDA and 0.1 to 57 moles of PMDA, or 92 to 99 moles of BPDA per 100 moles of the diamine.

In addition, the polyamic acid composition may contain 0.1 to 5 moles or 0.1 to 3 moles of BTDA per 100 moles of the diamine.

In order to improve heat resistance, thermal dimensional stability, and modulus, p-phenylenediamine may be used in a ratio of 0.8 to 1.0 mol per 1.0 mol of the total aromatic diamine. Compared to other aromatic diamines such as diaminophenyl ether, p-phenylenediamine is a linear monomer and has the advantage of reducing the thermal expansion coefficient of the resulting films.

In addition to p-phenylenediamine, the aromatic diamine may further comprise at least one aromatic diamine selected from the group consisting of: diaminophenyl ether, o-phenylenediamine, m-benzene Diamine, 2,6-diamino-pyridine, 4,4'-diaminodiphenyl benzene, 2-(4-aminophenyl)-1H-benzoxazol-5-amine, 2- (4-Aminophenyl)-5-aminobenzimidazole, 6-amino-2-(p-aminophenyl)benzoxazole, and 4,4''-diamino-p- Triphenyl.

In addition to the aromatic dianhydride and the aromatic diamine, the polyamic acid composition may contain a reaction solvent. The reaction solvent can be an amide-based aprotic solvent. Specifically, the reaction solvent may be at least one selected from the group consisting of: N,N'-dimethylformamide (DMF), N,N'-dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), acetonitrile, tetrahydrofuran (THF), 3-cresol (m-Cresol), 1,1,3,3-tetramethylurea (TMU), dimethyl Diene (DMSO), and γ-butyrolactone.

The polyamic acid solution is prepared from the polyamic acid composition. Specifically, the polyamic acid solution can be prepared by reacting the polyamic acid composition. The reaction can be carried out at 30 to 90°C.

The polyamide solution may have a viscosity of 1,000 to 20,000 cP at 23°C. Specifically, the polyamic acid solution may have a viscosity of 2,000 to 10,000 cP at 23°C.

The polyamic acid solution may have a weight average molecular weight of 10,000 to 200,000 or 15,000 to 150,000. Aromatic carboxylic acid

The aromatic carboxylic acid has at least four carboxyl groups. It acts to improve heat resistance, thermal dimensional stability and mechanical properties, while reducing the viscosity of the prepared polyamide solution. Specifically, the aromatic carboxylic acid may be an aromatic carboxylic acid having four carboxyl groups.

More specifically, the aromatic carboxylic acid may comprise at least one selected from the group consisting of pyrometic acid (PMA), 3,3',4,4'-biphenyltetracarboxylic acid (BPTA), 1,2,3,4-benzenetetracarboxylic acid, diphenylketone-3,3',4,4'-tetracarboxylic acid, pyrazinetetracarboxylic acid, 2,3,6,7- Naphthalene tetracarboxylic acid, and naphthalene-1,4,5,8-tetracarboxylic acid. More specifically, the aromatic carboxylic acid may comprise at least one selected from the group consisting of pyromic acid and 3,3',4,4'-biphenyltetracarboxylic acid. More specifically, the aromatic carboxylic acid may comprise pyromic acid or 3,3',4,4'-biphenyltetracarboxylic acid.

The polyamic acid composition may contain 1 to 8 moles of aromatic carboxylic acid per 100 moles of aromatic diamine. Specifically, the polyimide precursor composition may contain 1 to 7 moles or 1 to 6 moles of an aromatic carboxylic acid per 100 moles of the polyamide acid. Tertiary amine curing agent

The tertiary amine curing agent may comprise at least one selected from the group consisting of beta-picoline, isoquinoline, triethylenediamine, and pyridine. Specifically, the tertiary amine curing agent may comprise triethylenediamine and at least one selected from the group consisting of β-picoline, isoquinoline, and pyridine. Triethylenediamine acts to ensure that the polyimide precursor composition is cured at low temperatures and to improve the heat resistance of the resulting substrate.

The polyimide precursor composition may contain 0.1 to 50 moles of tertiary amine curing agent per 100 moles of polyimide. Specifically, the polyimide precursor composition may contain 0.1 to 2 moles of triethylenediamine per 100 moles of polyimide. More specifically, the polyimide precursor composition may comprise 0.1 to 2 moles of triethylenediamine and 5 to 50 moles of triethylenediamine per 100 moles of polyamide acid selected from the group consisting of: At least one of the group consisting of: beta-picoline, isoquinoline, and pyridine. Antioxidants

The antioxidant acts to reduce the reactivity of the amide groups in the polyimide precursor composition, thereby preventing damage caused by the reactivity of the amide groups during thermal processing in the process of making a substrate lead to oxidation.

The antioxidant may have a temperature of 400°C or higher or 5% by weight decomposition temperature of 400 to 480°C. Specifically, the antioxidant may be at least one selected from the group consisting of a compound represented by the following Chemical Formula 1, triethyl phosphate, and trimethyl phosphate. [Chemical formula 1]

In the above Chemical Formula 1, n is an integer from 0 to 4.

More specifically, the antioxidant may be triphenyl phosphate (TPP), where n is 0 (TPP, triphenyl phosphate), or may be a mixture of compounds where n is an integer from 1 to 4 (CAS 1003300 -73-9).

The polyimide precursor composition may comprise, based on the total weight of the polyimide precursor composition, 0.1 to 2% by weight of an antioxidant. Specifically, the polyimide precursor composition may include, based on the total weight of the polyimide precursor composition, 0.2 to 1.5% by weight or 0.2 to 1% by weight of an antioxidant. Polyimide substrate

Polyimide substrates according to the present invention are prepared by applying, drying and curing the polyimide precursor compositions described above. Specifically, the polyimide substrate can be prepared by applying the polyimide precursor composition as described above to a support substrate, drying and curing it, and then peeling it off.

The support substrate can be a glass substrate, a metal plate, or the like.

The drying and curing can be adjusted in terms of drying temperature and drying time depending on the thickness of the applied polyimide precursor composition. For example, the drying and curing can be carried out by a method comprising: drying at a temperature of 20 to 120°C for 5 to 60 minutes, increasing the temperature to 450°C at a rate of 1 to 8°C/min to 500°C, heat treatment at 450 to 500°C for 30 to 60 minutes, and cooling to 20 to 120°C at a rate of 1 to 8°C/min.

The polyimide substrate may have a glass transition temperature of 400 to 500°C, a modulus of 6 to 12 GPa, and a thermal expansion coefficient of 1 to 8 ppm/°C at 50 to 400°C. Specifically, the polyimide substrate may have a glass transition temperature of 420 to 480°C, a modulus of 6 to 11 GPa, and a thermal expansion coefficient of 2 to 8 ppm/°C at 50 to 400°C.

The polyimide substrate may have a pyrolysis temperature of 550 to 620° C. for 1% weight decomposition, and a transmittance of 40 to 80% for light at a wavelength of 550 nm based on a substrate thickness of 10 μm. Specifically, the polyimide substrate may have a pyrolysis temperature of 550 to 600°C for 1% weight decomposition, and a transmittance of 50 to 75% for light at a wavelength of 550 nm based on a substrate thickness of 10 µm .

The polyimide substrate may have a tensile strength of 200 to 500 MPa and a peel strength of 0.01 to 10 N/cm, and a decomposition time of 1 to 12 hours at 480° C. for 1% by weight decomposition. Specifically, the polyimide substrate may have a tensile strength of 250 to 460 MPa and a peel strength of 0.5 to 5 N/cm, and a decomposition time of 2 to 10 hours at 480° C. for 1% by weight decomposition.

The polyimide substrate can have an average thickness of 3 to 30 µm. Method for preparing a polyimide precursor composition

The method for preparing a polyimide precursor composition according to the present invention comprises: (1) preparing a polyimide solution by mixing and reacting an aromatic dianhydride and an aromatic diamine, the The aromatic dianhydride includes 3,4,3',4'-biphenyltetracarboxylic dianhydride (BPDA), and the aromatic diamine includes p-phenylenediamine (PPD); (2) the polyamide acid solution , a tertiary amine curing agent, and an antioxidant are mixed to prepare a mixture; and (3) the mixture is mixed with an aromatic carboxylic acid having at least four carboxyl groups. step 1)

In this step, a polyamic acid solution is prepared by mixing and reacting an aromatic dianhydride containing a 3,4,3',4'-diamine Benzenetetracarboxylic dianhydride (BPDA), the aromatic diamine includes p-phenylenediamine (PPD).

This step (1) can be carried out at 30 to 90°C.

In this step (1), a polyamide acid solution can be prepared by a reaction solvent, 3,4,3',4'-biphenyltetracarboxylic dianhydride, an additional aromatic dianhydride and an aromatic It is prepared by reacting a diamine, or by mixing and reacting 3,4,3',4'-biphenyltetracarboxylic dianhydride, an additional aromatic dianhydride, and an aromatic diamine. Specifically, the step (1) may include (1-1) making a reaction solvent, 3,4,3',4'-biphenyltetracarboxylic dianhydride, an additional aromatic dianhydride and an aromatic dianhydride Amines are mixed and reacted to prepare a first reactant having a viscosity of 100 to 10,000 cP at 23°C; and (1-2) an aromatic dianhydride solution (having a solids content of 5% by weight) is added in portions into the first reactant so that the viscosity of the first reactant at 23° C. is 1,000 to 20,000 cP, and the resultant is reacted to prepare a second reactant.

The additional aromatic dianhydride may be at least one selected from the group consisting of: pyromite dianhydride (PMDA), 3,3',4,4'-diphenylketone tetra Carboxylic dianhydride (BTDA), 2,3,3',4'-biphenyltetracarboxylic dianhydride, 1H,3H-naphtho[2,3-c:6,7-c']difuran-1 ,3,6,8-tetraketone, 2,3,6,7-naphthalene tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride, 4,4'-oxybisphthalate Formic anhydride, 4,4'-oxybis(2-benzofuran-1,3-dione), 4-[(1,3-dioxo-1,3-dihydro-2-benzofuran-5 -yl)oxy]-2-benzofuran-1,3-dione, and 5,5'-sulfonylbis-1,3-isobenzofurandione.

The reaction solvent can be an amide-based aprotic solvent. Specifically, the reaction solvent may be at least one selected from the group consisting of: N,N'-dimethylformamide, N,N'-dimethylacetamide, and N - Methylpyrrolidone (NMP).

The first reactant can be prepared by mixing 100 moles of aromatic diamine, 42 to 99 moles of BPDA, and 0.1 to 57 moles of additional aromatic dianhydride, or 100 moles of aromatic diamine Prepared by mixing with 92 to 99 moles of BPDA and reacting the mixture at 30 to 90°C.

The second reactant can be added batchwise to the first reactant by adding 0.1 to 57 moles of additional aromatic dianhydride solution per 100 moles of aromatic diamine, followed by annealing at 30 to 90°C. The product is obtained by reacting. In addition, the second reactant can be separated by adding 42 to 99 moles of BPDA per 100 moles of aromatic diamine to the first reactant and reacting the resultant at 30 to 90° C. Prepared by adding additional aromatic dianhydride solution in small batches to adjust the viscosity of the resultant to 1,000 to 20,000 cP at 23°C.

The solids content of the additional aromatic dianhydride solution may be 1 to 10% by weight or 2 to 8% by weight. The solvent of the additional aromatic dianhydride solution may be the same as the reaction solvent.

Additionally, the additional aromatic dianhydride solution may be added at intervals of 10 to 30 minutes. Furthermore, the second reactant may be stirred during the addition of the pyromic acid dianhydride solution.

The polyamide solution may have a viscosity of 1,000 to 20,000 cP at 23°C. Specifically, the polyamic acid solution may have a viscosity of 2,000 to 10,000 cP at 23°C. Step (2)

In this step, the polyamic acid solution, a tertiary amine curing agent and an antioxidant are mixed to prepare a mixture.

The tertiary amine curing agent and the antioxidant species are as defined in the polyimide precursor composition.

This step (2) can be carried out at 30 to 90°C. Specifically, this step (2) may be performed at 40 to 80°C.

The tertiary amine curing agent can be used in an amount of 0.1 to 50 moles per 100 moles of the polyamic acid. Specifically, the tertiary amine curing agent may comprise 5 to 50 moles of pyridine, β-picoline or isoquinoline, and 0.1 to 2 moles of triethylenediene per 100 moles of polyamide acid. amine.

The antioxidant may be used in an amount of 0.1 to 2% by weight based on the total weight of the polyimide precursor composition. Specifically, the antioxidant may be used in an amount of 0.2 to 1% by weight based on the total weight of the polyimide precursor composition. Step (3)

In this step, the mixture is mixed with an aromatic carboxylic acid having at least four carboxyl groups.

This step (3) can be carried out at 30 to 90°C. Specifically, this step (3) can be carried out at 40 to 80°C.

The aromatic carboxylic acid can be used in an amount of 1 to 8 moles per 100 moles of the aromatic diamine. Specifically, the aromatic carboxylic acid may be used in an amount of 1 to 6 moles per 100 moles of the aromatic diamine. SPECIFIC EXAMPLES OF IMPLEMENTING THE INVENTION

Hereinafter, the present invention is explained in detail by the following examples. The following examples are intended to further illustrate the present invention. The scope of the present invention is not limited to this. [ Example]

The abbreviations of the compounds used in the following Examples and Comparative Examples are as follows. -3,4,3',4'-biphenyltetracarboxylic dianhydride: BPDA -Pyromelic acid dianhydride: PMDA -p-phenylenediamine: PPD -3,3',4,4'-diphenyl Ketotetracarboxylic dianhydride: BTDA -N-Methylpyrrolidone: NMP -Pyromelic acid: PMA -3,3',4,4'-Biphenyltetracarboxylic acid: BPTA -Isoquinoline: IQ - Triethylenediamine: DABCO

In addition, the antioxidant used in the following Examples and Comparative Examples was ADK STAB FP-900L (hereinafter referred to as "FP-900L") of ADEKA Co., Ltd. Example 1 : Preparation of a polyimide precursor composition

300 g of NMP was charged into a 500 ml reactor equipped with a stirrer and nitrogen inlet/outlet while introducing nitrogen. After the temperature of the reactor was set to 30°C, 27.19 g of PPD, 35.74 g of BPDA, 0.87 g of BTDA, and 28.00 g of PMDA were added thereto, and the mixture was stirred until complete dissolution and reaction. When the reaction was complete, 1.44 g of PMDA was dissolved in NMP at a concentration of 5% by weight, which was added at 10 minute intervals until the viscosity of the mixture at 23°C reached 6,000 cP. After that, 1 mole of DABCO and 10 moles of IQ were added sequentially per 100 moles of polyamide. FP-900L was added at a concentration of 1% by weight based on the total weight of the polyamide, followed by stirring. Next, 4 moles of PMA were added per 100 moles of PPD. The resultant was stirred well until the reaction was complete. Next, NMP was added to adjust the total solids to 20% by weight, thereby preparing a polyimide precursor composition (viscosity of 3,500 cP at 23°C, solids of 20% by weight and 23,000 g/mol of weight average molecular weight). weight average molecular weight

The weight average molecular weight was measured using an HPLC 1260 Infinity Model II from Agilent Technologies. Specifically, the polyimide precursor composition was dissolved in a mobile phase NMP solution at a concentration of 1% by weight, filtered through a 0.45µm filter paper, and then used for measurement. The weight average molecular weight of the polyimide precursor composition was measured under the conditions of a PLgel 5mm Mixed-D column, a flow rate of 0.9 ml/min, and a measurement temperature of 50°C. Before the measurement, polystyrene was used as a standard substance under the same measurement conditions as described above to obtain a calibration curve for measuring the weight-average molecular weight. Viscosity and Storage Stability

The viscosity of the polyimide precursor composition was measured at room temperature (23°C) using a Rheostress 600 viscometer from Thermo Electron. Furthermore, after allowing it to stand at room temperature (23°C) for 30 days, the viscosity was measured again. The storage stability was evaluated as low if the viscosity change on storage was 10% or more, and the storage stability was evaluated as high if the viscosity change on storage was less than 10%. Example 2

A polyimide precursor composition (having a viscosity of 3,300 cP at 23°C, having a solids content of 20% and a weight average molecular weight of 22,000 g/mol) was prepared using the same method as in Example 1, except that no PMDA was used as the aromatic dianhydride, and BPDA was used in a content of 95 moles per 100 moles of PPD. Comparative Example 1

A polyimide precursor composition (having a viscosity of 270,000 cP at 23°C, having a solids content of 20% and a weight average molecular weight of 220,000 g/mol) was prepared using the same method as in Example 1, except that the 54 moles of PMDA was reacted with 100 moles of PPD as an aromatic dianhydride with an initial reactor temperature of 20°C and no tertiary amine curing agent, aromatic carboxylic acid components and antioxidants were used. In this case, it is difficult to obtain a uniform polyimide substrate in a thin film due to the high viscosity, which makes it impossible to measure the physical properties of the substrate. It was also confirmed that the storage stability of the polyimide precursor composition itself was low. Comparative Example 2

A polyimide precursor composition (having a viscosity of 4,000 cP at 23° C., having a solids content of 20% and a weight average molecular weight of 24,000 g/mol) was prepared using the same method as in Comparative Example 1, except that the 50 mol of PMDA was reacted with 100 mol of PPD as an aromatic dianhydride. In this case, the storage stability of the composition over time is low. After a period of time, it is difficult to obtain a uniform polyimide substrate as a thin film due to a significant reduction in viscosity, which makes it impossible to measure the physical properties of the substrate. Comparative Examples 3 to 6

製備例：製備聚醯亞胺基材 Each polyimide precursor composition was prepared using the same method as in Example 1, except that the aromatic dianhydride component, aromatic carboxylic acid component, tertiary amine curing agent, and Antioxidants. [Table 1]

Preparation Example: Preparation of Polyimide Substrate

The polyimide precursor compositions of Examples 1 and 2 and Comparative Examples 1 to 6 were individually rotated at high speed at 1,500 rpm or higher to remove air bubbles. Thereafter, the defoamed polyimide precursor composition was applied to a glass substrate using a spin coater. Next, it was dried under 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, and cooled at a rate of 2°C/min to 30°C, thereby preparing a polyimide substrate. After that, it was soaked in distilled water to peel the polyimide substrate from the glass substrate. The resulting polyimide substrate had a thickness of 10 µm.

The thickness of the prepared polyimide substrate was measured using an electronic film thickness meter from Anritsu. Test Example: Evaluation of Physical Properties

The polyimide substrates prepared in the preparation examples were subjected to physical quality measurement by the following methods. The results are shown in Table 2. (1) Glass transition temperature

The polyimide substrate was cut to a width of 4 mm and a length of 20 mm and then used a Dynamic Mechanical Analysis model Q800 from TA at 5°C/min over a temperature range between room temperature and 550°C and the glass transition temperature measurement was carried out under nitrogen atmosphere. The glass transition temperature is determined by the maximum peak of tan δ calculated from the ratio of storage modulus to loss modulus. (2) 1% weight decomposition temperature

The 1% weight decomposition temperature was measured using a Thermogravimetric Analysis Model Q50 from TA. The polyimide substrate was heated to 150°C at a rate of 10°C/min under nitrogen atmosphere and allowed to stand at a constant temperature for 30 minutes to remove moisture. Next, the temperature was raised to 600°C at a rate of 10°C/min to measure the temperature for 1% weight loss. (3) Coefficient of Thermal Expansion (CTE)

The coefficient of thermal expansion was measured using a Thermomechanical Analysis Model Q400 from TA. The polyimide substrate was cut into a width of 2 mm and a length of 10 mm, and was heated from room temperature to 480° C. at a rate of 10° C./min under a nitrogen atmosphere and a tension of 0.05 N, followed by 10° C./min. rate for cooling. The slope of the region between 50°C and 400°C is measured. (4) Modulus and tensile strength

The polyimide substrate was cut to a width of 10 mm and a length of 40 mm, and the modulus and tensile strength were measured according to ASTM D-882 using Instron 5564 UTM from Instron. In this case, the cross head speed used for the measurement was 5 mm/min. (5) Transmittance of light with a wavelength of 550 nm

Model Lambda 465 from Perkin Elmer was used as the UV-Vis spectrophotometer. Transmittance in 550 nm mode was measured. [Table 2]

As demonstrated in Tables 1 and 2, the polyimide precursor compositions of Examples 1 and 2 have low viscosity and high storage stability, even though they have a high solids content of 20% by weight. In addition, the polyimide substrates prepared from the polyimide precursor compositions of Examples 1 and 2 are excellent in heat resistance, modulus, tensile strength and light transmittance, and also have low thermal expansion coefficient.

(none)

Claims (19)

A polyimide precursor composition, comprising: a polyamide solution prepared from a polyamide composition comprising an aromatic dianhydride and an aromatic diamine , the aromatic dianhydride comprises 3,4,3',4'-biphenyl tetracarboxylic dianhydride (BPDA), the aromatic diamine comprises p-phenylenediamine (PPD); an aromatic having at least four carboxyl groups a tertiary amine curing agent; and an antioxidant, wherein the antioxidant is a compound represented by the following chemical formula 1:

where n is 1. The polyimide precursor composition of claim 1, wherein the aromatic dianhydride further comprises at least one aromatic dianhydride selected from the group consisting of: pyromite dianhydride (PMDA) , 3,3',4,4'-diphenylketone tetracarboxylic dianhydride (BTDA), 2,3,3',4'-biphenyltetracarboxylic dianhydride, 1H,3H-naphtho[2 ,3-c: 6,7-c']difuran-1,3,6,8-tetraone, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalene Tetracarboxylic dianhydride, 4,4'-oxybisphthalic anhydride, 4,4'-oxybis(2-benzofuran-1,3-dione), 4-[(1,3-dione) Oxy-1,3-dihydro-2-benzofuran-5-yl)oxy]-2-benzofuran-1,3-dione, and 5,5'-sulfonylbis-1,3 - isobenzofurandione. The polyimide precursor composition of claim 2, comprising 0.1 to 70 moles of additional aromatic dianhydride per 100 moles of aromatic diamine. The polyimide precursor composition of claim 1, wherein the aromatic carboxylic acid comprises at least one selected from the group consisting of: pyromelic acid (PMA), 3,3', 4,4'-biphenyltetracarboxylic acid (BPTA), 1,2,3,4-benzenetetracarboxylic acid, diphenyl ketone-3,3',4,4'-tetracarboxylic acid, pyrazinetetracarboxylic acid acid, 2,3,6,7-naphthalenetetracarboxylic acid, and naphthalene-1,4,5,8-tetracarboxylic acid. The polyimide precursor composition of claim 1, wherein the polyimide composition comprises 1 to 8 moles of aromatic carboxylic acid per 100 moles of aromatic diamine. The polyimide precursor composition according to claim 1, wherein the tertiary amine curing agent comprises at least one selected from the group consisting of: β-picoline, isoquinoline, triphenylene diamines, and pyridine. The polyimide precursor composition of claim 6, wherein the tertiary amine curing agent comprises triethylenediamine and at least one selected from the group consisting of: β-picoline, isocyanide Quinoline, and pyridine. The polyimide precursor composition according to claim 7, which comprises 0.1 to 2 mol of triethylenediamine per 100 mol of polyamide. The polyimide precursor composition according to claim 1, comprising 1 to 8 mol of aromatic carboxylic acid and 0.1 to 50 mol of tertiary amine curing agent per 100 mol of polyamide acid. Such as the polyimide precursor composition of claim 1, wherein the antioxidant has a temperature of 400°C or higher for 5% by weight decomposition. The polyimide precursor composition of claim 1, comprising, based on the total weight of the polyimide precursor composition, 0.1 to 2% by weight of an antioxidant. A polyimide substrate is prepared by applying, drying and curing the polyimide precursor composition of any one of claims 1 to 11. The polyimide substrate of claim 12, wherein the drying and curing are carried out by a method comprising the following: drying at a temperature of 20 to 120° C. for 5 to 60 minutes, with a being 1 to 8 The temperature is raised to 450 to 500°C at a rate of 1 to 500°C, heat treated at 450 to 500°C for 30 to 60 minutes, and cooled to 20 to 120°C at a rate of 1 to 8°C/minute. The polyimide substrate of claim 12, having a glass transition temperature of 400 to 500°C, a modulus of 6 to 12 GPa, and a thermal expansion coefficient of 1 to 8 ppm/°C at 50 to 400°C. The polyimide substrate of claim 12 having a pyrolysis temperature of 1% by weight decomposition of 550 to 620°C and a 40 to 80% for light having a wavelength of 550 nm based on a substrate thickness of 10 μm Transmittance. A method for preparing a polyimide precursor composition, comprising: (1) preparing a polyimide solution by mixing and reacting an aromatic dianhydride and an aromatic diamine, the aromatic The aromatic dianhydride includes 3,4,3',4'-biphenyltetracarboxylic dianhydride (BPDA), and the aromatic diamine includes p-phenylenediamine (PPD); (2) the polyamide acid solution, A tertiary amine curing agent and an antioxidant are mixed to prepare a mixture, wherein the antioxidant is a compound represented by the following chemical formula 1:

wherein n is 1; and (3) mixing the mixture with an aromatic carboxylic acid having at least four carboxyl groups. The method for preparing a polyimide precursor composition as claimed in claim 16, wherein the step (1) comprises: (1-1) making a reaction solvent, 3,4,3',4'-biphenyl Tetracarboxylic dianhydride, an additional aromatic dianhydride, and an aromatic diamine are mixed and reacted to prepare a first reactant having a viscosity of 100 to 10,000 cP at 23°C; and (1-2) the An aromatic dianhydride solution (having a solids content of 5% by weight) was added in portions to the first reactant such that the viscosity of the first reactant at 23°C was 1,000 to 20,000 cP, and the resultant was reacted to A second reactant is prepared. The method for preparing a polyimide precursor composition as claimed in claim 16, wherein the step (1) is carried out at 30 to 90° C., and the polyimide in step (1) is heated at 23° C. It has a viscosity of 1,000 to 20,000 cP. The method for preparing a polyimide precursor composition as claimed in claim 16, wherein the step (2) is carried out at 30 to 90°C, and the step (3) is carried out at 30 to 90°C.