KR20220170242A - Polyamide, polybenzooxazole formed therefrom, and polybenzooxazole film including the polybenzooxazole - Google Patents

Abstract

The present invention provides polyamide represented by chemical formula 1, and polybenzoxazole and a polybenzoxazole film formed therefrom. In chemical formula 1, Ar_3, Ar_4, X_1 to X_3 R_4 are the same as defined in the detailed description. Another aspect provides the polybenzoxazole film having light transmittance, excellent heat resistance, and high refractive index by containing the above-described polybenzoxazole.

Description

Polyamide, polybenzooxazole formed therefrom, and polybenzooxazole film including the polybenzooxazole}

The present invention relates to polyamides, polybenzoxazoles and polybenzoxazole films formed therefrom, and more particularly to novel polyamides, polybenzoxazoles and polybenzoxazole films formed therefrom.

Polybenzoxazole is a polymer having an oxazole group in the main chain, and is a super engineering plastic having excellent heat resistance, mechanical strength, dimensional stability, and insulating properties. In particular, aromatic polybenzoxazole is used for high-strength, high-heat-resistance applications such as automobile materials and aerospace materials as well as daily life products due to its excellent mechanical properties and electrical insulation properties due to its rigid main chain structure, and is used in various electronic materials fields. is widely applied in

Although polybenzoxazole has the above-mentioned excellent properties, it is colored by light absorption by conjugated double bonds and formation of intramolecular or intermolecular charge-transfer complex (CTC) due to light absorption of polybenzoxazole. A phenomenon occurs, which causes a decrease in light transmittance, which makes it difficult to apply to optical materials. In particular, aromatic polymers are widely used in insulating films for semiconductors, such as interlayer materials for semiconductors and metal wiring due to their excellent heat resistance, but low dielectric properties are expected as the degree of integration of devices increases. In order to overcome this, research on reducing the permittivity of polybenzoxazole using various inorganic particles has been widely conducted, but these composite materials have problems in that chemical stability is low and light transmittance is reduced.

In order to solve these optical problems, polymer composite materials using inorganic nanoparticles have been recently developed, and they exhibit a dielectric constant of 2 or less, but the polymer composite materials have low chemical stability, high light loss, and complicated manufacturing processes. has a downside

Accordingly, recent technologies have not been able to provide a polybenzoxazole film that is excellent enough to be applied to advanced integrated devices, and exhibits mechanical durability, heat resistance, and ease of manufacturing process better than general polybenzoxazole films, while permitting dielectric constant, There is an urgent need for the development of a polybenzoxazole film that has improved light transmittance and can be used for semiconductor substrate materials.

According to one aspect, it is to provide a novel polyamide.

Another aspect is to provide a polybenzoxazole formed from the polyamide described above.

Another aspect is to provide a polybenzoxazole film having light transmittance, excellent heat resistance, and a high refractive index by containing the above-described polybenzoxazole.

According to one aspect, a polyamide represented by Formula 1 is provided.

[Formula 1]

In Formula 1, Ar ₃ and Ar ₄ are each independently selected from the group consisting of Formulas 3-1 to 3-3,

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

In Formulas 1-1 to 1-3, R ₁ to R ₃ are each independently selected from the group consisting of hydrogen, fluorine, a C1 to C30 alkyl group, and a C1 to C30 perfluoroalkyl group;

X ₁ to X ₃ are independently of each other oxygen (O), sulfur (S), sulfur monoxide (SO), sulfur dioxide (SO ₂ ), selenium (Se) selenium dioxide (SeO ₂ ), tellurium (Te), or dioxide Tellurium (TeO ₂ ),

R ₄ is selected from the group consisting of a divalent substituted or unsubstituted aromatic cyclic organic group and a divalent substituted or unsubstituted aliphatic cyclic organic group;

n is a polymerization degree and is an integer of 10 to 1,000.

According to another aspect, there is provided a polybenzoxazole, which is an oxazolization reaction product of the above-described polyamide.

According to another aspect, the above-described polybenzoxazole film is provided.

The polybenzoxazole film of the present invention is an optical material exhibiting high refractive index and excellent light transmittance and excellent dielectric constant, transparency and heat resistance. In addition, the polybenzoxazole film has reduced crystallinity and reduced intramolecular anisotropy, so that the glass transition temperature is high and the birefringence is low. This polybenzoxazole film has mechanical durability, heat resistance, and is easy to manufacture, so it can be usefully used as a semiconductor substrate material.

1 is a ¹ H-NMR nuclear magnetic resonance (NMR) analysis spectrum of the compound of Formula 5 prepared according to Preparation Example 1.
2 is a ¹³ C-NMR nuclear magnetic resonance (NMR) analysis spectrum of the compound of Formula 5 prepared according to Preparation Example 1.
3 is a graph showing the results of differential scanning calorimetry (DSC) measurement of polybenzoxazole films prepared according to Example 2 and Comparative Examples 1 and 2.
4 is a graph showing the results of thermogravimetric analysis of polybenzoxazole films prepared according to Example 2 and Comparative Examples 1 and 2.
5 is a graph showing the results of measuring the refractive index of polybenzoxazole films prepared according to Example 2 and Comparative Examples 1 and 2.
6 is a graph showing the results of ultraviolet-visible spectroscopy (UV-Vis) measurement of polybenzoxazole films prepared according to Example 2 and Comparative Examples 1 and 2.

Hereinafter, a polyamide according to an embodiment, a polybenzoxazole formed therefrom, and a polybenzoxazole film will be described in detail.

Polybenzoxazole is a very promising material as an electronic material because of its excellent mechanical properties and electrical insulation properties. By the way, polybenzoxazole is difficult to apply as an optical material due to a coloring phenomenon and a decrease in light transmittance, so research on reducing the dielectric constant of polybenzoxazole is in progress. However, until now, polybenzoxazoles having satisfactory permittivity characteristics and excellent chemical stability and light transmittance have not been developed.

Accordingly, the inventors of the present invention have solved the above-mentioned problems, and thus have excellent mechanical durability and heat resistance, are easy to manufacture, and have improved dielectric constant, light transmittance, etc. Provided is polyamide, which is a usable material for manufacturing.

The polyamide of the present invention is a polymer represented by Formula 1 below.

[Formula 1]

In Formula 1, Ar ₃ and Ar ₄ are each independently selected from the group consisting of Formulas 3-1 to 3-3,

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

In Formulas 1-1 to 1-3, R ₁ to R ₃ are each independently selected from the group consisting of hydrogen, fluorine, a C1 to C30 alkyl group, and a C1 to C30 perfluoroalkyl group;

X ₁ to X ₃ are independently of each other oxygen (O), sulfur (S), sulfur monoxide (SO), sulfur dioxide (SO ₂ ), selenium (Se) selenium dioxide (SeO ₂ ), tellurium (Te), or dioxide Tellurium (TeO ₂ ),

R ₄ is selected from the group consisting of a divalent substituted or unsubstituted aromatic cyclic organic group and a divalent substituted or unsubstituted aliphatic cyclic organic group;

n is a polymerization degree and is an integer of 10 to 1,000, an integer of 20 to 500, an integer of 50 to 120, or an integer of 80 to 110.

The C1 to C30 alkyl group is, for example, a C1 to C10 alkyl group, specifically a methyl group, an ethyl group, a propyl group, or a butyl group. And C1 to C30 perfluoroalkyl groups include, for example, CF3, CF2CF3, and the like.

The divalent aromatic cyclic organic group in R ₄ means an arylene group, for example, an unsubstituted or substituted phenylene group, specifically a phenylene group or a 4-hydroxyphenyl group. Examples of the divalent aliphatic cyclic organic group include a C1-C20 alkylene group and a C4-C20 cycloalkylene group.

The group consisting of a substituted aromatic cyclic organic group and a substituted aliphatic cyclic organic group of R ₄ may have a hydroxyl group, a methyl group, a halogen atom, or the like as a substituent.

In Formula 1, R ₄ may be selected from groups represented by Formulas 2-1 to 2-11 below.

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

[Formula 2-4] [Formula 2-5] [Formula 2-6]

[Formula 2-7] [Formula 2-8] [Formula 2-9]

[Formula 2-10] [Formula 2-11]

In Chemical Formulas 2-1 to 2-11, * represents a bonding site.

Polyamide according to an embodiment may be prepared by reacting a dihydroxy diaminobenzene compound represented by Chemical Formula 9 below with a dicarboxylic acid chloride represented by Chemical Formula 10 below.

[Formula 9]

In Formula 9, X ₁ to X ₃ are independently of each other oxygen (O), sulfur (S), sulfur monoxide (SO), sulfur dioxide (SO ₂ ), selenium (Se) selenium dioxide (SeO ₂ ), tellurium (Te ), is selected from the group consisting of tellurium dioxide (TeO ₂ ),

Ar ₁ and Ar ₂ are each independently selected from the group consisting of Formulas 9-1 to 9-3,

[Formula 9-1] [Formula 9-2] [Formula 1-3]

In Chemical Formulas 9-1 to 9-3, * represents a binding site;

R ₁ to R ₃ are each independently selected from the group consisting of hydrogen, fluorine, a C1 to C30 alkyl group and a C1 to C30 perfluoroalkyl group,

[Formula 10]

In Formula 10, Ar ₃ is selected from the group consisting of a divalent aromatic cyclic organic group and a divalent aliphatic cyclic organic group.

Ar ₃ of Formula 10 may be represented by Formulas 2-1 to 10-11 below.

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

[Formula 2-4] [Formula 2-5] [Formula 2-6]

[Formula 2-7] [Formula 2-8] [Formula 2-9]

[Formula 2-10] [Formula 2-11]

When the dihydroxy diaminobenzene compound of Chemical Formula 9 includes a benzene ring in the main chain, transfer of electrons of the benzene ring can easily occur. This may result in absorption of light in the visible ray region, which may cause a browning phenomenon in which the color of the compound is changed, and light transmittance may be lowered. And the dihydroxy diamino benzene compound is oxygen (O), sulfur (S), sulfur monoxide (SO), sulfur dioxide (SO ₂ ), selenium (Se) selenium dioxide (SeO ₂ ), tellurium (Te ), tellurium dioxide (TeO ₂ ), and many other elements with strong electronegativity and high polarizability. Such an element having a strong electronegativity can reduce the transition of π electrons in a molecule, thereby reducing the absorption of light in the visible ray region.

In addition, the dihydroxy diamino benzene compound has a structure in which aromatics are connected to a flexible sulfur element in a molecule, and thus, polymers and polybenzoxazole films prepared using the same have reduced crystallinity and reduced intramolecular anisotropy. Therefore, the glass transition temperature can be high and the birefringence can also be kept low.

The dicarboxylic acid chloride compound of Chemical Formula 10 includes a plurality of elements with high polarizability such as oxygen (O), sulfur (S), sulfur monoxide (SO), sulfur dioxide (SO ₂ ), and selenium (Se) in the benzene ring. As a precursor, a polymer and polybenzoxazole film prepared using this as a monomer may exhibit a high refractive index and excellent light transmittance. In addition, the dicarboxylic acid chloride compound has a structure in which aromatics are connected to a flexible sulfur element in a molecule, and thus, polymers and polybenzoxazole films prepared using the same have reduced crystallinity and reduced intramolecular anisotropy, The glass transition temperature can be high and the birefringence can also be kept low.

A polybenzoxazole film containing polyamide obtained by using the compound of Formula 9 and Formula 10 and polybenzoxazole formed therefrom may exhibit a high refractive index and excellent light transmittance. In the dihydroxy diamino benzene compound, phosphorus has a large electron cloud radius and a low molar volume, so that polyamide and polybenzoxazole films obtained using the phosphorus may have a high refractive index.

According to another aspect, polybenzoxazole and a polybenzoxazole film, which are the above-described oxazolization reaction products of polyamide, are provided. This polybenzoxazole film has a high refractive index and is used as an optical material with excellent transparency and heat resistance.

Polyamide according to one embodiment is one selected from polymers represented by Chemical Formulas 2 to 4 below.

[Formula 2]

[Formula 3]

[Formula 4]

In formulas (2) to (4), n is a degree of polymerization and is an integer of 10 to 1,000, 20 to 500, 50 to 120, or 80 to 110.

Polyamide according to one embodiment has a number average molecular weight of 10,000 to 500,000 g/mol. When having such a number average molecular weight, the dielectric constant and optical properties of polyamide are excellent.

Polybenzoxazole according to an embodiment may be prepared through an oxazolization reaction of polyamide.

Polybenzoxazole is a polymer represented by Formula 5 below.

[Formula 5]

In Formula 5, Ar ₃ and Ar ₄ are each independently selected from the group consisting of Formulas 5-1 to 5-3,

[Formula 5-1] [Formula 5-2] [Formula 5-3]

In Formulas 5-1 to 5-3, R ₁ to R ₃ are each independently selected from the group consisting of hydrogen, fluorine, a C1 to C30 alkyl group, and a C1 to C30 perfluoroalkyl group;

R ₄ represents a divalent aromatic cyclic organic group, which means an arylene group, such as an unsubstituted or substituted phenylene group, specifically a phenylene group. Examples of the divalent aliphatic cyclic organic group include a C1-C20 alkylene group and a C4-C20 cycloalkylene group. R ₄ is one selected from groups represented by Chemical Formulas 2-1 to 2-11.

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

[Formula 2-4] [Formula 2-5] [Formula 2-6]

[Formula 2-7] [Formula 2-8] [Formula 2-9]

[Formula 2-10] [Formula 2-11]

In Chemical Formulas 2-1 to 2-11, * represents a bonding site.

The polybenzoxazole of the present invention may include, for example, one polymer selected from polymers represented by Chemical Formulas 6 to 8 below.

[Formula 6]

[Formula 7]

[Formula 8]

In Formulas 6 to 8, n is an integer of 10 to 1,000, for example, an integer of 20 to 800, an integer of 20 to 500, an integer of 50 to 120, or an integer of 80 to 110.

A look at the polyamide of the present invention and a method for preparing polybenzoxazole using the same are as follows.

Polyamide is prepared by mixing a dihydroxy diaminobenzene compound of Formula 9 and a dicarboxylic acid chloride of Formula 10 with a solvent, and then polymerizing the mixture under an inert gas atmosphere.

[Formula 9]

In Formula 9, X ₁ to X ₃ are independently of each other oxygen (O), sulfur (S), sulfur monoxide (SO), sulfur dioxide (SO ₂ ), selenium (Se) selenium dioxide (SeO ₂ ), tellurium (Te ), is selected from the group consisting of tellurium dioxide (TeO ₂ ),

Ar ₁ and Ar ₂ are each independently selected from the group consisting of Formulas 9-1 to 9-3,

[Formula 9-1] [Formula 9-2] [Formula 1-3]

In Chemical Formulas 9-1 to 9-3, * represents a binding site;

R ₁ to R ₃ are each independently selected from the group consisting of hydrogen, fluorine, a C1 to C30 alkyl group and a C1 to C30 perfluoroalkyl group,

[Formula 10]

In Formula 10, Ar ₃ is selected from the group consisting of a divalent aromatic cyclic organic group and a divalent aliphatic cyclic organic group.

Examples of the compound of Formula 10 include the compound of Formula 11 below.

[Formula 11]

As the solvent, for example, N-methylpyrrolidone, tetrahydrofuran and the like are used.

An inert gas atmosphere is formed using argon, nitrogen, or the like.

In the polymerization reaction described above, reaction conditions such as temperature may vary depending on the type of dihydroxy diamino benzene compound and dicarboxylic acid chloride used. For example, the polymerization reaction may be carried out in a range of 25°C to 150°C.

A desired polybenzoxazole may be obtained by carrying out an oxazolization reaction of the polyamide.

In the oxazolization reaction, dehydration cyclization is performed by heating, and oxazolization is performed at a high temperature of, for example, 250 to 350 ° C.

Intrinsic viscosity of polyamide according to one embodiment is 0.67 to 0.82 dL/g.

In one embodiment, a polybenzoxazole film may be prepared using the polyamide. The polybenzoxazole film may exhibit a refractive index (wavelength: about 637 nm) between 1.74 and 1.79. The refractive index may be, for example, 1.7400 to 1.7866 or 1.76 to 1.7845.

The polybenzoxazole film may exhibit birefringence of 0.001 to 0.004, or 0.0012 to 0.0035. The birefringence is, for example, 0.00115 to 0.00315. And the transmittance of the polybenzoxazole film is 78.0 to 90.3%, for example, 78.0 to 90.0% at a wavelength of 650 nm, and the dielectric constant is 0.0053 to 0.0087. And the UV blocking wavelength range of the polybenzoxazole film is 450 to 460 nm, for example, 452 to 465 nm.

The polybenzoxazole film of the present invention is very useful as an optical film when it has the above-described refractive index, transmittance, birefringence and dielectric constant properties. And it has light transmittance, excellent heat resistance, and high refractive index. And the 10% weight reduction temperature of the polybenzoxazole film according to one embodiment is 510 to 560 ℃. In this specification, the term "10% weight loss temperature" means the temperature when the total weight of the film or compound is reduced to 90% of the total weight of the film or compound at room temperature. That is, it means the temperature when the weight is reduced by 10% compared to the total weight at room temperature.

In addition, the polybenzoxazole and polybenzoxazole film of the present invention can be applied to a glass fiber composite film, an eyeglass lens, a light diffusion film, an encapsulant, an infrared camera, and the like. The polybenzoxazole film can be used as an optical film, and such an optical film is useful as a film and coating material when manufacturing microlenses, functional optical coatings, and high-intensity LEDs (Light Emitting Diodes). And the polybenzoxazole film is useful as an LED encapsulant or substrate.

Hereinafter, the present invention will be described with reference to the following examples, but this does not mean that the present invention is limited only to the following examples.

(Preparation of dicarboxylic acid chloride)

Preparation Example 1

Referring to Scheme 1 below, 150 ml of tetrahydrofuran, 10 g of 4-fluorobenzoic acid, 11.68 g of di-tert-butyl dicarbonate, and 6.48 g of 4-dimethylamino pyridine were added to a 500 ml round flask and refluxed for 12 hours. It was reacted under the condition to obtain a white solid. After dissolving 7.0 g of the solid content in 100 ml of dimethylformamide, 14.6 g of 4,4-thiobisbenzenethiol was added and reacted at 120 ^° C for 12 hours to obtain a white solid. This was added to hydrochloric acid and boiled to obtain 16.7 g of a white solid. Thereafter, 10 g of the white solid was put into a 250 ml round flask, thionyl chloride was added, and boiled to obtain 5.7 g of dicarboxylic acid chloride represented by Chemical Formula 11. Accordingly, a dicarboxylic acid chloride having a thiocer group could be prepared.

[Scheme 1]

[Formula 11]

(manufacture of polyamide)

Example 1

2.27 g of the compound of Formula 11 prepared according to Preparation Example 1, 2 g of 4,4-bis(4-amino-3-hydroxyphenolthio)diphenylsulfide (3S-DA) represented by Formula 9-1, and After adding 9.96 g of N-methyl-2-pyrrolidone, it was reacted for 24 hours at room temperature (25 ° C.) under a nitrogen atmosphere to obtain a polyamide solution with a solid content of 30 wt% containing polyamide represented by Formula 4. manufactured. The intrinsic viscosity of the polyamide solidified from the polyamide solution was 0.67. (Measurement conditions: 30°C, N-methyl-2-pyrrolidone solution).

[Formula 9-1]

[Formula 4]

In Formula 4, n is 100.

(Polybenzoxazole Film)

Example 2

After casting the polyamide solution containing polyamide of Chemical Formula 4 prepared according to Preparation Example 1 on a silicon substrate, it was subjected to casting at 120°C for 30 minutes, at 200°C for 30 minutes, at 250°C for 30 minutes, and at 300°C for 30 minutes. By heating, a polybenzoxazole film containing polybenzoxazole represented by Formula 8 and having a thickness of about 10 um was prepared.

[Formula 8]

In Formula 8, n is 100.

Comparative Example 1: Preparation of polybenzoxazole film

Except for using Isophthaloyl Chloride instead of the compound of Formula 11 in Preparation Example 1, polyamide and polybenzoate were sequentially carried out in the same manner as in Preparation Example 1, Example 1 and Example 2. Oxazole films were prepared respectively.

Comparative Example 2: Preparation of polybenzoxazole film

Except for using 4,4-oxybis(benzoyl chloride) (4,4'-Oxybis(benzoyl Chloride)) instead of the compound of Formula 11 of Preparation Example 1, Preparation Example 1, Example 1 and Example 2 Polyamide and polybenzoxazole films were prepared sequentially according to the same method.

Evaluation Example 1: Nuclear Magnetic Resonance Analysis (NMR)

The results of NMR analysis of the compound of Formula 11 prepared according to Preparation Example 1 are shown in FIGS. 1 and 2. NMR analysis was performed using a 600 MHz NMR spectrometer manufacturers (Agilent Technologies, Inc. and Bruker BioSpin Corp.). FIG. 1 is a ¹ H-NMR analysis spectrum and FIG. 2 is a ¹³ C-NMR analysis spectrum.

Referring to Figure 1a, the hydrogen peaks of the aromatic rings indicated by a and b at chemical shifts (δ) of 7.85, 7.43, 7.39, and 7.30, respectively, were confirmed, confirming the structure of the compound of Formula 5.

Referring to FIG. 1b, peaks a, b, c, d, e, f, and g appear at chemical shifts (δ) of 167.17, 142.04, 135.27, 133.97, 132.27, 130.75, and 128.90 ppm, confirming the structure of the compound of Formula 5. could

Evaluation Example 2: Differential scanning calorimetry (DSC) and thermogravimetric analyzer (TGA) analysis

For the polybenzoxazole film of Example 2 and the polybenzoxazole films prepared according to Comparative Examples 1 and 2, the glass transition temperature of the polymer was confirmed through differential scanning calorimetry (DSC) analysis. In addition, heat resistance was measured through a thermogravimetric analyzer (TGA) of the polybenzoxazole film, and the results are shown in Table 1 and FIGS. 3 to 4 below. Figure 3 shows the DSC analysis result of polybenzoxazole, Figure 4 is a graph showing the TGA result of polybenzoxazole.

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

division T _g (℃) T _5% (℃) T _10% (℃) Example 2 185.38 487.79 496.13 Comparative Example 1 193.93 507.07 527.45 Comparative Example 2 190.52 491.28 505.07

In Table 1, T _g represents the glass transition temperature, and T _5% and T _10% represents a 5% weight loss temperature and a 10% weight loss temperature, respectively, and means the temperature when the total weight of the film is reduced to 95% or 90% of the total weight of the film or compound at room temperature. That is, it means the temperature when the weight is reduced by 5% or 10% compared to the total weight at room temperature.

As a result of the evaluation, it can be seen that all of the polybenzoxazole films of Example 2 lose 10% in weight at a temperature of 500 ° C or higher, and the glass transition temperature is shown at a temperature of 180 ° C or higher.

Evaluation Example 3: Refractive index of polybenzoxazole film, transmittance by wavelength and UV cut-off wavelength

For the polybenzoxazole film prepared according to Example 2 prepared using the polyamide solution of Example 1 and the polybenzoxazoles prepared according to Comparative Examples 1 and 2, a UV-visible spectrometer was used for each wavelength. Transmittance and UV cut-off wavelength were measured. The refractive index and birefringence were analyzed with a prism coupler, and the results are shown in Table 2.

polyamide dihydroxy diamino benzene carboxylic acid
chloride refractive index
at 637 nm birefringence
at 637 nm Example 2 Formula 9-1 Example 1 1.784521 0.00315 Comparative Example 1 Formula 9-1 isophthaloyl chloride 1.750817 0.00115 Comparative Example 2 Formula 9-1 4,4-oxylbis(benzoyl chloride) 1.74007 0.00133

Referring to Table 2, it was confirmed that the polybenzoxazole film prepared according to Example 2 exhibited an excellent refractive index by showing a refractive index of 1.78 or more. And, referring to Table 2, the polybenzoxazole film prepared using the polyamide solution according to Example 2 exhibited an excellent birefringence of around 0.0030.

The refractive index characteristics of the polybenzoxazole film of Example 2 are shown in FIG. 5 . Referring to this, it was found that the polybenzoxazole film of Example 2 had better refractive index characteristics than the polybenzoxazole films of Comparative Examples 1 and 2. In particular, in the case of the polybenzoxazole film prepared in Example 2, it can be confirmed that it has the highest refractive index of 1.78767 at 637 nm, which is because it contains a large amount of sulfur having a high polarizability.

In addition, the transmittance of the polybenzoxazole film of Example 2 and the polybenzoxazole film prepared according to Comparative Examples 1 and 2 is shown in FIG. 6 together.

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

Claims (10)

Polyamide represented by Formula 1 below:
[Formula 1]

In Formula 1, Ar ₃ and Ar ₄ are each independently selected from the group consisting of Formulas 3-1 to 3-3,
[Formula 1-1] [Formula 1-2] [Formula 1-3]

In Formulas 1-1 to 1-3, R ₁ to R ₃ are each independently selected from the group consisting of hydrogen, fluorine, a C1 to C30 alkyl group, and a C1 to C30 perfluoroalkyl group;
X ₁ to X ₃ are independently of each other oxygen (O), sulfur (S), sulfur monoxide (SO), sulfur dioxide (SO ₂ ), selenium (Se) selenium dioxide (SeO ₂ ), tellurium (Te), or dioxide Tellurium (TeO ₂ ),
R ₄ is selected from the group consisting of a divalent substituted or unsubstituted aromatic cyclic organic group and a divalent substituted or unsubstituted aliphatic cyclic organic group;
n is a polymerization degree and is an integer of 10 to 1,000. The polyamide according to claim 1, wherein the polyamide is selected from polymers represented by Formulas 2 to 4 below:
[Formula 2]

[Formula 3]

[Formula 4]

In Formulas 2 to 4, n is an integer of 10 to 1,000. Section 1 or a polybenzoxazole which is an oxazolization reaction product of the polyamide of claim 2. The polybenzoxazole according to claim 3, wherein the polybenzoxazole is a polymer represented by Formula 5 below:
[Formula 5]

In Formula 5, Ar ₃ and Ar ₄ are each independently selected from the group consisting of Formulas 5-1 to 5-3,
[Formula 5-1] [Formula 5-2] [Formula 5-3]

In Formulas 5-1 to 5-3, R ₁ to R ₃ are each independently selected from the group consisting of hydrogen, fluorine, a C1 to C30 alkyl group, and a C1 to C30 perfluoroalkyl group;
It is selected from the group consisting of a substituted or unsubstituted aromatic cyclic organic group and a divalent substituted or unsubstituted aliphatic cyclic organic group,
n is an integer from 10 to 1,000. The polybenzoxazole according to claim 4, wherein R ₄ is one selected from groups represented by Formulas 2-1 to 2-11.
[Formula 2-1] [Formula 2-2] [Formula 2-3]

[Formula 2-4] [Formula 2-5] [Formula 2-6]

[Formula 2-7] [Formula 2-8] [Formula 2-9]

[Formula 2-10] [Formula 2-11]

In Chemical Formulas 2-1 to 2-11, * represents a bonding site. The polybenzoxazole according to claim 3, wherein the polybenzoxazole is a polymer represented by Formulas 6 to 8:
[Formula 6]

[Formula 7]

[Formula 8]

In Formulas 6 to 8, n is an integer of 10 to 1,000. A polybenzoxazole film comprising the polybenzoxazole of claim 3. The polybenzoxazole film according to claim 7, wherein the polybenzoxazole film has a refractive index of 1.74 to 1.79 and a birefringence of the polybenzoxazole film of 0.001 to 0.004. The polybenzoxazole film according to claim 7, wherein the polybenzoxazole film has a transmittance of 78.0 to 90.3% at a wavelength of 650 nm, a permittivity of 0.0053 to 0.0087, and a UV cut-off wavelength range of 450 nm to 460 nm. The polybenzoxazole film according to claim 7, wherein the 10% weight reduction temperature of the polybenzoxazole film is 510 °C to 560 °C.

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