KR102602466B1 - Polyamic acid, polyimide formed thereof, and polyimide film - Google Patents

Abstract

The present invention provides a polyamic acid containing a first repeating unit represented by the following formula (1) and a second repeating unit represented by the following formula (2), and a polyimide and polyimide film formed therefrom.
[Formula 1]

[Formula 2]

In Formulas 1 and 2, m and n, R ₁ to R ₄ , Ar ₁ and Ar ₂ are as defined in the detailed description.

Description

Polyamic acid, polyimide formed therefrom, and polyimide film {Polyamic acid, polyimide formed therefrom, and polyimide film}

The present invention relates to a polyamic acid, a polyimide formed therefrom, and a polyimide film containing the polyimide. More specifically, it relates to a novel polyamic acid having excellent heat resistance and low dielectric constant, a polyimide formed therefrom, and a polyimide film. It's about film.

Polyimide is a polymer containing imide bonds in the main chain and has heat resistance and chemical resistance derived from the chemical stability of imide. In particular, aromatic polyimide is used for high-strength, high-heat resistance purposes such as automobile materials and aerospace materials as well as daily necessities due to its excellent mechanical properties and electrical insulation properties due to its rigid main chain structure. In addition, it is widely used in various electronic materials fields as an insulating film for semiconductors, such as interlayer materials for semiconductors and metal wiring, and as device integration becomes more advanced, low dielectric properties are expected.

In particular, photocurable polyimide has the advantage of being able to replace photoresist in the photolithography process of forming electrode patterns in semiconductor organic thin-film transistors, thereby simplifying the process. Since polyimide has insulating properties, it can be widely used as an interlayer material in the field of electronic materials such as semiconductors using photocurable polyimide films.

Meanwhile, polymer composite materials using inorganic nanoparticles have recently been developed, and although they exhibit a dielectric constant of 2 or less, these polymer composite materials have the disadvantage of low chemical stability and a complicated manufacturing process.

Accordingly, prior technologies do not provide polyimide films excellent enough to be applied to advanced integrated devices, and while exhibiting mechanical durability, heat resistance, and ease of manufacturing process compared to conventional polyimide films, the dielectric constant has been improved so that they can be used for semiconductor substrates, etc. There is an urgent need for the development of photocurable polyimide films.

According to one aspect, a novel polyamic acid manufactured using fluorine-based diamine is provided.

According to another aspect, there is provided a polyimide formed from the above-described polyamic acid.

According to another aspect, there is provided a polyimide film containing the above-described polyimide and having excellent heat resistance and low dielectric constant.

According to one aspect, a polyamic acid is provided including a first repeating unit represented by the following formula (1) and a second repeating unit represented by the following formula (2).

[Formula 1]

[Formula 2]

In Formula 1 and Formula 2, m and n are mole fractions, 0<m<1, 0<n<1, the sum of m and n is 1,

R ₁ to R ₄ are polymerizable functional groups and are independently one or more selected from a vinyl group, an acrylate group, and a methacrylate group,

Ar ₁ and Ar ₂ are selected differently from each other and are selected from the group consisting of the following formulas 1-1 to 1-3,

[Formula 1-1] [Formula 1-2] [Formula 1-2]

, ,

In Formulas 1-1 to 1-3, * represents the bonding position,

R ₅ and R ₆ are independently selected from the group consisting of hydrogen, a C1 to C30 alkyl group, or a trifluoromethyl (CF ₃ ) group.

According to another aspect, polyimide, which is an imidization reaction product of the above-described polyamic acid, is provided.

According to another aspect, a polyimide film containing the above-described polyimide is provided.

The polyamic acid of the present invention and the polyimide formed therefrom have a structure in which aromatics are linked to flexible 16-period elements within the molecule. As a result, the polyamic acid and polyimide have a lower crystallinity and anisotropy within the molecule is reduced, resulting in a glass transition temperature. It can be high and the birefringence can also be kept low. As a result, polyimide film realizes excellent heat resistance and chemical/mechanical durability.

Hereinafter, the polyamic acid of the present invention, the polyimide formed therefrom, and the polyimide film containing the polyimide will be described in more detail.

A polyamic acid comprising a first repeating unit represented by the following formula (1) and a second repeating unit represented by the following formula (2) is provided.

[Formula 1]

[Formula 2]

In Formula 1 and Formula 2, m and n are mole fractions, 0<m<1, 0<n<1, the sum of m and n is 1,

R ₁ to R ₄ are polymerizable functional groups and are independently one or more selected from a vinyl group, an acrylate group, and a methacrylate group,

Ar ₁ and Ar ₂ are selected differently from each other and are selected from the group consisting of the following formulas 1-1 to 1-3,

[Formula 1-1] [Formula 1-2] [Formula 1-2]

, ,

In Formulas 1-1 to 1-3, * represents the bonding position,

R ₅ and R ₆ are independently selected from the group consisting of hydrogen, a C1 to C30 alkyl group, or a trifluoromethyl (CF ₃ ) group.

In the polyamic acid, m and n represent the mole fraction of the first repeating unit and the second repeating unit, respectively, and are 0.1 to 0.9, 0.3 to 0.7, or 0.4 to 0.6.

The polymerizable functional group is -C(=O)O-CH ₂ CH ₂ OC(=O)C(=CH ₂ )CH ₃ , -C(=O)O-CH ₂ OC(=O)C(=CH ₂ )CH ₃ , -C(=O)O-CH ₂ CH ₂ CH ₂ OC(=O)C(=CH ₂ )CH ₃ , -C(=O)O-CH ₂ CH ₂ OC(=O) CH(=CH ₂ ), -C(=O)O-CH ₂ OC(=O)CH(=CH ₂ )CH ₃ , or -C(=O)O-CH ₂ CH ₂ CH ₂ OC(=O )CH(=CH ₂ ).

delete

The polyamic acid can be prepared through the reaction of a polymerizable functional group-containing compound with at least one selected from dianhydride represented by the following formula (1) and diamine represented by formulas (2a) to (2c).

[Formula 1]

[Formula 2a] [Formula 2b] [Formula 2c]

In Formulas 2a to 2c, R ₅ or R ₆ is each independently selected from the group consisting of hydrogen, a C1 to C30 alkyl group, or trifluoromethyl (CF ₃ ).

Compounds containing polymerizable functional groups include hydroxyethyl methacrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-propylheptyl acrylate, sec-butyl methacrylate, and tert-butyl methacrylate. Latex, methyl acrylate, isopropyl acrylate, cyclohexyl methacrylate, 2-methylcyclohexyl methacrylate, dicyclopentenyl acrylate, dicyclopentanyl acrylate, dicyclopentenyl methacrylate, dicyclofentanyl Methacrylate, 1-adamantyl acrylate, 1-adamantyl methacrylate, dicyclofentanyloxyethyl methacrylate, isoboronyl methacrylate, dicyclohexyl acrylate, 2-methylcyclohexyl acrylate ester, dicyclofentanyloxyethyl acrylate, isoboronyl acrylate, phenyl methacrylate, phenyl acrylate, benzyl acrylate, 2-hydroxyethyl methacrylate, and 1,6-hexanedioldiacrylate. Use the back.

The polyamic acid according to one embodiment contains a large number of highly electronegative elements, such as oxygen (O) and trifluoromethyl sulfur (CF ₃ ), in the benzene ring, and these can reduce the movement of π electrons within the molecule. It can reduce the absorption of light in the visible light range. In addition, when polyamic acid contains a ditrifluoromethyl (CF ₃ ) structure, it has a large number of fluorine atoms with a large molecular radius due to the inclusion of this structure, which has the effect of minimizing interactions between the polymer main chains, resulting in a high aromatic ring density. can be lowered. Accordingly, polymers and polyimide films manufactured using diamine containing a trifluoromethyl (CF ₃ ) group may exhibit low refractive index and dielectric constant. In addition, the carbon-fluorine bond contained in the diamine has a high bonding energy, so it is structurally very stable and has excellent chemical stability. And since the trifluoromethyl (CF ₃ ) structure of diamine has a large number of fluorine atoms with a large molecular radius, it has the effect of minimizing interactions between the polymer main chains, thereby reducing the high aromatic ring density.

The polyamic acid of the present invention has a weight average molecular weight of 3,000 to 30,000 g/mol and a polydispersity index of 1.5 to 2. And the degree of polymerization of the polyamic acid is controlled to obtain the above-described weight average molecular weight, for example, in the range of 1 to 100, specifically 1 to 10.

Polyamic acid is a polymer represented by the following chemical formula.

[Formula 5-1]

In Formula 5-1, R ₁ to R ₄ are polymerizable functional groups, and may be selected from, for example, a substituted or unsubstituted vinyl group having 1 to 10 carbon atoms, an acrylate group, or a methacrylate group. Ar1 and Ar2, m and n are as described above.

In Formula 5-1, m:n is a molar ratio of 9:1 to 1:9, 9:1 to 5:5, or 7:3 to 5:5. The degree of polymerization of the polyamic acid of Formula 5-1 is 1 to 100, for example, 1 to 10.

In the polyamic acid, the first repeating unit includes a repeating unit represented by the following formula (3) or a first repeating unit represented by the formula (4), and the second repeating unit is a second repeating unit represented by the following formula (5).

<Formula 3>

<Formula 4>

<Formula 5>

In Formulas 3 to 5, m and n are mole fractions of 0<m<1 and 0<n<1.

In Formulas 3 to 5, the mixing molar ratio of the first repeating unit and the second repeating unit is 9:1 to 1:9, 9:1 to 5:5, or 7:3 to 5:5. In Formulas 3 to 5, the degree of polymerization of the polyamic acid is 1 to 100, for example, 1 to 10.

For example, the polyamic acid is a polymer containing a repeating unit represented by Formula 3 and a repeating unit represented by Formula 5.

Polyamic acid is a polymer represented, for example, by the following formula 5-2.

[Formula 5-2]

In Formula 5-2, m:n is a molar ratio of 9:1 to 1:9, 9:1 to 5:5, or 7:3 to 5:5.

The degree of polymerization of the polyamic acid of Formula 5-2 is 1 to 100, for example, 1 to 10.

According to another aspect, a polyimide prepared by imidizing the above-described polyamic acid is provided. Polyimide is an imidization reaction product of polyamic acid.

In an exemplary embodiment, the polyimide includes a first repeating unit represented by Formula 6 below and a second repeating unit represented by Formula 7 below.

[Formula 6]

[Formula 7]

In Formulas 6 and 7, m and n are mole fractions, and the sum of m and n is 1, 0<m<1, 0<n<1, Ar ₁ and Ar ₂ are selected differently from each other, and the formula 1- is selected from the group consisting of 1 to 1-3,

[Formula 1-1] [Formula 1-2] [Formula 1-3]

, ,

In Formulas 1-1 to 1-3, * represents a bonding position, and R ₅ and R ₆ are independently selected from the group consisting of hydrogen, a C1 to C30 alkyl group, or trifluoromethyl (CF ₃ ).

In Formulas 6 and 7, m:n is a molar ratio of 9:1 to 1:9, 9:1 to 5:5, or 7:3 to 5:5. The degree of polymerization of the polyimides of Formulas 6 and 7 is 1 to 100, for example, 1 to 10.

For example, the polyimide includes a first repeating unit represented by the following formula (9) and a second repeating unit represented by the following formula (10).

<Formula 9>

In Formula 9, m is 0.1 to 0.9,

<Formula 10>

In Formula 10, n is 0.1 to 0.9.

In Formulas 9 and 10, m:n is a molar ratio of 9:1 to 1:9, 9:1 to 5:5, or 7:3 to 5:5.

The degree of polymerization of the polyimides of Formulas 9 and 10 is 1 to 100, for example, 1 to 10.

According to another aspect, a polyimide film containing the above-described polyimide is provided. The polyimide film can be manufactured by casting on a substrate such as glass or silicon wafer.

As the coating method, spin coating method, doctor blade method, flow coating method, spray coating method, etc. commonly used in the industry can be selected and used, and any process that can produce a polyimide film by coating the polyamic acid can be freely used. may be selected, and the present invention is not limited by this casting method.

The polyimide film of the present invention can have excellent heat resistance and chemical and mechanical durability. The polyimide film has a temperature of about 410°C to 500°C compared to the total weight of the polyimide film at room temperature. Total weight can be reduced by 90%. And the polyimide film of the present invention can exhibit low refractive index and dielectric constant.

The polyimide film may exhibit a refractive index between about 1.62 and 1.66.

In addition, according to one embodiment of the present invention, the dianhydride and diamine monomers have a structure in which aromatics are linked to a flexible 16-period element within the molecule, and as a result, polymers and polyimide films prepared using them have crystals. As the property decreases, the anisotropy within the molecule decreases, so the glass transition temperature may be high.

Hereinafter, the present invention will be described in more detail through examples. These examples are only for illustrating the present invention, and it will be obvious to those skilled in the art that the scope of the present invention should not be construed as limited by these examples.

(Manufacture of polyamic acid)

Comparative Manufacturing Example 1

In a 100ml round flask, 3.1 g of 4,4'-oxydiphthalic anhydride (ODPA), 0.243 ml of hydroxyethyl methacrylate (HEMA), and 1,4-diazabicyclo[2.2.2]octane (DABCO). After adding 0.23 g and 12.5 g of N-methyl-2-pyrrolidone (NMP), stirring was performed for 1 hour at 45 ^o C under a nitrogen atmosphere. After cooling the reactor to 25 ^o C, 1.8 g of m-tolidine and 5 g of N-methyl-2-pyrrolidone (NMP) were added and stirred at 45 ^o C for 2 hours and 30 minutes under a nitrogen atmosphere. Cooled to ^o C. After adding 2.6 ml of trifluoroacetic anhydride to this solution and stirring for 20 minutes, 2.48 ml of hydroxyethyl methacrylate (HEMA) was added and reacted at 45 ^o C for 20 hours to form a polyamic acid solution. was manufactured. This reaction solution was added dropwise to distilled water and the precipitate was dried to obtain solidified polyamic acid as a bright yellow solid.

Comparative Manufacturing Example 2

In a 100ml round flask, 3.1 g of 4,4'-oxydiphthalic anhydride (ODPA), 0.243 ml of hydroxyethyl methacrylate (HEMA), and 1,4-diazabicyclo[2.2.2]octane (DABCO). After adding 0.23 g and 12.5 g of N-methyl-2-pyrrolidone (NMP), stirring was performed for 1 hour at 45 ^o C under a nitrogen atmosphere. After cooling the reactor to 25 ^o C, 1.62 g of m-tolidine, 0.09 g of m-phenylenediamine (m-PDA), and 5 g of N-methyl-2-pyrrolidone (NMP) were added and stirred under nitrogen atmosphere. After stirring at 45 ^o C for 2 hours and 30 minutes, it was cooled to 25 ^o C. After adding 2.6 ml of trifluoroacetic anhydride to this solution and stirring for 20 minutes, 2.48 ml of hydroxyethyl methacrylate (HEMA) was added and reacted at 45 ^o C for 20 hours to form a polyamic acid solution. was manufactured. This reaction solution was added dropwise to distilled water and the precipitate was dried to obtain solidified polyamic acid as a bright yellow solid.

Comparative Manufacturing Example 3

In a 100ml round flask, 3.1 g of 4,4'-oxydiphthalic anhydride (ODPA), 0.243 ml of hydroxyethyl methacrylate (HEMA), and 1,4-diazabicyclo[2.2.2]octane (DABCO). After adding 0.23 g and 12.5 g of N-methyl-2-pyrrolidone (NMP), stirring was performed for 1 hour at 45 ^o C under a nitrogen atmosphere. After cooling the reactor to 25 ^o C, 1.26 g of m-tolidine, 0.28 g of m-phenylenediamine (m-PDA), and 5 g of N-methyl-2-pyrrolidone (NMP) were added and stirred under nitrogen atmosphere. After stirring at 45 ^o C for 2 hours and 30 minutes, it was cooled to 25 ^o C. After adding 2.6 ml of trifluoroacetic anhydride to this solution and stirring for 20 minutes, 2.48 ml of hydroxyethyl methacrylate (HEMA) was added and reacted at 45 ^o C for 20 hours to form a polyamic acid solution. was manufactured. This reaction solution was added dropwise to distilled water and the precipitate was dried to obtain solidified polyamic acid as a bright yellow solid.

Comparative Manufacturing Example 4

In a 100ml round flask, 3.1 g of 4,4'-oxydiphthalic anhydride (ODPA), 0.243 ml of hydroxyethyl methacrylate (HEMA), and 1,4-diazabicyclo[2.2.2]octane (DABCO). After adding 0.23 g and 12.5 g of N-methyl-2-pyrrolidone (NMP), stirring was performed for 1 hour at 45 ^o C under a nitrogen atmosphere. After cooling the reactor to 25 ^o C, 0.9 g of m-tolidine, 0.46 g of m-phenylenediamine (m-PDA), and 5 g of N-methyl-2-pyrrolidone (NMP) were added and reacted under nitrogen atmosphere. After stirring at 45 ^o C for 2 hours and 30 minutes, it was cooled to 25 ^o C. After adding 2.6 ml of trifluoroacetic anhydride to this solution and stirring for 20 minutes, 2.48 ml of hydroxyethyl methacrylate (HEMA) was added and reacted at 45°C for 20 hours to prepare a polyamic acid solution. Manufactured. This reaction solution was added dropwise to distilled water and the precipitate was dried to obtain solidified polyamic acid as a bright yellow solid.

Manufacturing Example 1

In a 100ml round flask, 3.1 g of 4,4'-oxydiphthalic anhydride (ODPA), 0.243 ml of 2-hydroxyethyl methacrylate (HEMA), and 1,4-diazabicyclo[2.2.2]octane ( After adding 0.23 g of DABCO) and 12.5 g of N-methyl-2-pyrrolidone (NMP), stirring was performed for 1 hour at 45°C under a nitrogen atmosphere.

After cooling the reactor to 25 ^o C, 1.62 g of m-tolidine, 0.27 g of 2,2'-bis(trifluoromethyl)benzidine (TFMB), 5 g of N-methyl-2-pyrrolidone (NMP) was added and stirred at 45 ^o C for 2 hours and 30 minutes under a nitrogen atmosphere, and then cooled to 25 ^o C. After adding 2.6 ml of trifluoroacetic anhydride to this solution and stirring for 20 minutes, 2.48 ml of hydroxyethyl methacrylate (HEMA) was added and reacted at 45 ^o C for 20 hours to form a polyamic acid solution. was manufactured. This reaction solution was added dropwise to distilled water and the precipitate was dried to obtain solidified polyamic acid as a bright yellow solid.

The polyamic acid is a polymer represented by the following Chemical Formula 5-2, and the weight average molecular weight of the polyamic acid is about 10,500.

[Formula 5-2]

In Formula 5-2, m and n are 0.9 and 0.1.

Production example 2

In a 100ml round flask, 3.1 g of 4,4'-oxydiphthalic anhydride (ODPA), 0.243 ml of hydroxyethyl methacrylate (HEMA), and 1,4-diazabicyclo[2.2.2]octane (DABCO). After adding 0.23 g and 12.5 g of N-methyl-2-pyrrolidone (NMP), stirring was performed at 45°C for 1 hour under a nitrogen atmosphere. After cooling the reactor to 25°C, 1.26 g of m-tolidine, 0.81 g of 2,2'-bis(trifluoromethyl)benzidine (TFMB), and 5 g of N-methyl-2-pyrrolidone (NMP) were added. Added and stirred at 45 ^o C for 2 hours and 30 minutes under a nitrogen atmosphere, then cooled to 25 ^o C. After adding 2.6 ml of trifluoroacetic anhydride to this solution and stirring for 20 minutes, 2.48 ml of hydroxyethyl methacrylate (HEMA) was added and reacted at 45°C for 20 hours to prepare a polyamic acid solution. Manufactured. This reaction solution was added dropwise to distilled water and the precipitate was dried to obtain solidified polyamic acid as a bright yellow solid. Compared to the polyamic acid of Preparation Example 1, this polyamic acid is a polymer represented by Chemical Formula 5-2, and m and n are 0.7 to 0.3.

The polyamic acid is a polymer represented by the following Chemical Formula 5-2, and the weight average molecular weight of the polyamic acid is about 8,800.

[Formula 5-2]

In Formula 5-2, m and n are 0.7 and 0.3.

Production example 3

In a 100ml round flask, 3.1 g of 4,4'-oxydiphthalic anhydride (ODPA), 0.243 ml of hydroxyethyl methacrylate (HEMA), and 1,4-diazabicyclo[2.2.2]octane (DABCO). After adding 0.23 g and 12.5 g of N-methyl-2-pyrrolidone (NMP), stirring was performed for 1 hour at 45 ^o C under a nitrogen atmosphere. After cooling the reactor to 25 ^o C, 0.9 g of m-tolidine, 1.36 g of 2,2'-bis(trifluoromethyl)benzidine (TFMB), and 5 g of N-methyl-2-pyrrolidone (NMP) were added. was added and stirred at 45°C for 2 hours and 30 minutes under a nitrogen atmosphere, and then cooled to 25°C. After adding 2.6 ml of trifluoroacetic anhydride to this solution and stirring for 20 minutes, 2.48 ml of hydroxyethyl methacrylate (HEMA) was added and reacted at 45 ^o C for 20 hours to form a polyamic acid solution. was manufactured. This reaction solution was added dropwise to distilled water and the precipitate was dried to obtain solidified polyamic acid as a bright yellow solid. Compared to the polyamic acid of Preparation Example 1, this polyamic acid is a polymer represented by Chemical Formula 5-2, and m and n are 0.5 and 0.5, respectively.

The polyamic acid is a polymer represented by the following Chemical Formula 5-2, and the weight average molecular weight of the polyamic acid is about 9,100.

[Formula 5-2]

In Formula 5-2, m and n are 0.5 and 0.5.

(Manufacture of polyimide and polyimide film)

Example 1

A solution of the polyamic acid of Preparation Example 1 with a solid content of 30 wt% dissolved in N-methyl-2-pyrrolidone (NMP) was spin-coated on a silicon substrate, followed by 2 hours at 90°C and 1 hour at 375°C. A polyimide film containing polyimide was prepared by heat treatment for a while.

Example 2-3

A polyimide film containing polyimide was manufactured in the same manner as in Example 1, except that the polyamic acid of Preparation Example 2 and the polyamic acid of Preparation Example 3 were used instead of the polyamic acid of Preparation Example 1.

Example 4

The polyamic acid of Preparation Example 1 was dissolved in N-methyl-2-pyrrolidone (NMP) at a solid content of 30 wt%, and the photoinitiator (1-phenyl-1,2-propanedione-2-( O - A solution containing ethoxycarboxy)oxime) and tetraethylene glycol dimethacrylate, a crosslinking agent, was spin-coated on a silicon substrate, followed by heat treatment at 95°C for 2 minutes and ultraviolet curing at 110 ^° C for 2 minutes to produce polyethylene glycol. A polyimide film containing mead and polyimide can be obtained.

Example 5-6

A polyimide film containing polyimide was manufactured in the same manner as in Example 4, except that the polyamic acid of Preparation Example 2 and the polyamic acid of Preparation Example 3 were used instead of the polyamic acid of Preparation Example 1.

Comparative Example 1-4

A polyimide film containing polyimide was manufactured in the same manner as in Example 1, except that the polyamic acids of Comparative Preparation Examples 1 to 4 were used instead of the polyamic acid of Preparation Example 1.

Comparative Example 5-8

A polyimide film containing polyimide was manufactured in the same manner as in Example 4, except that the polyamic acids of Comparative Preparation Examples 1 to 4 were used instead of the polyamic acid of Preparation Example 1.

Evaluation Example 1: Gel permeation chromatography (GPC) analysis

Using gel permeation chromatography (GPC), the weight average molecular weight, number average molecular weight, and polydispersity index of the polyamic acid prepared according to Preparation Examples 1 to 3 and Comparative Preparation Examples 1 to 4 of the present invention were measured. Saved. 4 mg of polyamic acid was measured using 1 ml of solvent dimethylformamide (DMF) solution, and the analysis results are shown in Table 1.

polyamic acid Diamine molar ratio Mw Mn Polydispersity index m-tolidine m-PDA TFMB Comparative Manufacturing Example 1 10 0 0 11,090 5,540 2.002 Comparative Manufacturing Example 2 9 One 0 7,100 4,170 1.699 Comparative Manufacturing Example 3 7 3 0 6,830 4,030 1.694 Comparative Manufacturing Example 4 5 5 0 5,270 3,410 1.544 Manufacturing Example 1 9 0 One 8,830 4,910 1.798 Production example 2 7 0 3 9,130 4,890 1.867 Production example 3 5 0 5 6,260 3,660 1.708

It was confirmed that the polyamic acid according to Preparation Examples 1 to 3 had a weight average molecular weight of about 5,000 to 11,000 g/mol, a number average molecular weight of about 3,000 to 6,000 g/mol, and a polydispersity index of 1.5 to 2.

Evaluation Example 2: Refractive index, birefringence and dielectric constant of polyimide film

The refractive index of the polyimide film coated on the silicon substrate according to Examples 1 to 3 and Comparative Examples 1 to 4 was analyzed using a prism coupler. In addition, the dielectric constant of the polyimide film was calculated using the average refractive index at a wavelength of 637 nm, and the results are listed in Table 2.

polyamic acid Diamine molar ratio Refractive index at 637 nm birefringence permittivity m-tolidine m-PDA TFMB Comparative Example 1 10 0 0 1.6953 0.0189 2.874 Comparative Example 2 9 One 0 1.6981 0.0093 2.884 Comparative Example 3 7 3 0 1.6926 0.0009 2.865 Comparative Example 4 5 5 0 1.6916 0.0017 2.862 Example 1 9 0 One 1.6760 0.0094 2.809 Example 2 7 0 3 1.6680 0.0095 2.782 Example 3 5 0 5 1.6623 0.0056 2.763

As shown in Table 2, the polyimide film manufactured using the polyamic acid according to Examples 1 to 3 contains trifluoromethyl (CF ₃ ) and diamine containing trifluoromethyl (CF ₃ ). It was confirmed that as the content increased, it had a lower refractive index, birefringence, and dielectric constant compared to the other cases (Comparative Examples 1 to 4).

In addition, the refractive index, birefringence, and dielectric constant of the polyimide films prepared in Examples 4-6 and Comparative Examples 5-8 were evaluated in the same manner as the refractive index, birefringence, and dielectric constant evaluation methods of the polyimide in Example 1.

As a result of the above-mentioned evaluation, the refractive index, birefringence, and dielectric constant of the polyimide film prepared according to Examples 4-6 and Comparative Example 8 were at the same level as those of the polyimide film of Example 1.

Evaluation Example 3: DSC and TGA analysis of polyimide film

The glass transition temperature was confirmed through DSC analysis for a total of eight polyimide films manufactured using the polyamic acid solutions according to Preparation Examples 1 to 3 and Comparative Preparation Examples 1 to 4, and heat resistance was measured through TGA analysis. The results are shown in Table 3 below. Additionally, the DSC analysis results are shown in Figure 1, and the TGA analysis results are shown in Table 1 below.

DSC analysis was performed using TA Instruments' Q20, which was measured at a temperature increase rate of 5 per minute under a nitrogen atmosphere and confirmed by heating from room temperature to 300 ^o C. And TGA analysis was performed using TA Instruments' Q50, measured at a temperature increase rate of 10 per minute under a nitrogen atmosphere, and confirmed by heating from room temperature to 800°C.

polyamic acid Diamine molar ratio Glass transition temperature (℃) 10% weight loss temperature (℃) m-tolidine m-PDA TFMB Comparative Example 1 10 0 0 247.4 453.5 Comparative Example 2 9 One 0 242.9 422.7 Comparative Example 3 7 3 0 240.6 422.1 Comparative Example 4 5 5 0 246.0 421.5 Example 1 9 0 One 247.2 430.7 Example 2 7 0 3 241.7 414.4 Example 3 5 0 5 243.1 433.2

In Table 3 above, the 10% weight reduction temperature is indicated, meaning the temperature when the total weight of the film is reduced to 90% of the total weight of the film or compound at room temperature. In other words, it means the temperature when the weight decreases by 10% compared to the total weight at room temperature.

As shown in Table 3, the polyimide films manufactured using the polyamic acid solutions according to Examples 1 to 3 all lost 10% of their weight at a temperature of 400 ^o C or higher, confirming that they had excellent heat resistance.

The embodiments of the present invention described above should not be construed as limiting the technical idea of the present invention. The scope of protection of the present invention is limited only by the matters stated in the claims, and those skilled in the art can improve and change the technical idea of the present invention into various forms. Accordingly, such improvements and changes will fall within the scope of protection of the present invention as long as they are obvious to those skilled in the art.

Claims (13)

A polyamic acid represented by the following formula 5-2, having a weight average molecular weight of 3,000 to 30,000 g/mol, and a polydispersity index of 1.5 to 2:
[Formula 5-2]

In Formula 5-2, m is 0.5 to 0.9, and n is 0.1 to 0.5. delete delete delete delete delete Polyimide, which is an imidization reaction product of the polyamic acid of claim 1. delete delete A polyimide film containing the polyimide according to claim 7. The polyimide film of claim 10, wherein the polyimide film has a refractive index of 1.6 to 1.7. The polyimide film of claim 10, wherein the polyimide film has a dielectric constant of 2.64 to 2.81. The polyimide film of claim 10, wherein at a temperature of 400°C to 510°C, the total weight of the polyimide film decreases to 90% of the total weight of the polyimide film at room temperature.