KR20130075202A - Aramid fiber and method for manufacturing the same - Google Patents

Abstract

PURPOSE: An aramid fiber, and a manufacturing method thereof are provided to manufacture without using a sulfuric acid solvent with high productivity. CONSTITUTION: An armid fiber comprises: aromatic poly amid having recurring unit of chemical formula 1. The aromatic polyamide comprises 2.4-3.0 of polydispersity index (PDI). A manufacturing method thereof comprises: dissolving aromatic diamine comprising substituted aromatic diamine whose benzene ring hydrogen is substituted for -CN, -Cl, -SO_3H, or -CF_3 in an organic solvent; adding aromatic diacid halide to the organic solvent at least as same molar amount as the aromatic diamine to obtain a polymerization solution comprising aromatic polyamide; extruding the polymerization solution through spinneret; and forming filament by passing the extruded polymerization solution through a coagulant.

Description

Technical Field The present invention relates to an aramid fiber,

More particularly, the present invention relates to an aramid fiber and a production method thereof, and more particularly, to an aramid fiber which can be produced without using a sulfuric acid solvent by using a polymerization solution directly as a polymerization solution and can be produced with high productivity .

Aromatic polyamides, commonly referred to as aramids, include para-aramids having a structure in which benzene rings are linearly connected through an amide group (CONH), and meta-based aramids that are not.

Para-aramid has excellent properties such as high strength, high elasticity and low shrinkage. The thin thread with a thickness of 5 mm manufactured from it has a strength enough to lift a 2 - tonne automobile and is used not only for bulletproof but also for various applications in high - tech industry in aerospace sector.

In addition, since aramid is carbonized black at a temperature of 500 ° C or higher, it is also in the spotlight where high heat resistance is required.

The method for producing aramid fibers is well described in the applicant's Korean Patent No. 10-0910537. According to this registered patent, an aromatic diamine is dissolved in a polymerization solvent to prepare a mixed solution, and aromatic dieside is added thereto to prepare an aramid polymer. The aramid fiber is finally completed by dissolving the aramid polymer in a sulfuric acid solvent to prepare a spinning dope, spinning the spinning dope, followed by coagulation, washing, and drying.

However, when the aramid fiber is produced through such a process, since a solid state aramid polymer is prepared and then dissolved again in a sulfuric acid solvent to prepare a spinning dope, the spinning process is complicated and harmful to the human body, And the durability is degraded due to corrosion.

Furthermore, since the sulfuric acid solvent used to dissolve the aramid polymer having high chemical resistance and removed after the spinning causes environmental pollution, it has to be appropriately treated after use. The cost for treating such spent sulfuric acid is not only economical .

Accordingly, the present invention relates to an aramid fiber and a method for producing the same that can prevent the problems caused by the above limitations and disadvantages of the related art.

One aspect of the present invention is to provide an aramid fiber that can be produced with high productivity without the use of a sulfuric acid solvent.

Another aspect of the present invention is to provide a method of producing aramid fibers without the use of a sulfuric acid solvent by using the polymerization solution directly as a radial process, but capable of producing aramid fibers at a high spinning speed.

In addition to the above-mentioned aspects of the present invention, other features and advantages of the present invention will be described below, or from such description will be clearly understood by those skilled in the art.

According to one aspect of the present invention, there is provided an aromatic polyamide having a repeating unit represented by the following formula (1)

[Formula 1]

Wherein R ₁ is -CN, -Cl, -SO ₃ H, or -CF ₃ , Ar ₁ and Ar ₂ are each independently aromatic hydrocarbons having 1 to 4 benzene rings, Aramid fibers characterized by having a polydispersity index (PDI) of 2.4 to 3.0.

According to another aspect of the present invention, an aromatic diamine comprising a substituted aromatic diamine in which the hydrogen of the benzene ring is substituted with -CN, -Cl, -SO ₃ H, or -CF ₃ is dissolved in an organic solvent ; Then, adding aromatic diacid halide to the organic solvent at least in the same molar amount as the aromatic diamine to obtain a polymerization solution containing an aromatic polyamide; Extruding the polymer solution through a spinneret; And forming the filaments by causing the extruded polymer solution to pass through the coagulation liquid.

The foregoing general description of the present invention is intended to be illustrative of or explaining the present invention, but does not limit the scope of the present invention.

According to the present invention, aramid fibers can be produced without the use of a sulfuric acid solvent by directly using a polymerization solution with an irradiance profile. Therefore, the problems such as the complexity of the manufacturing process due to the use of the sulfuric acid solvent, the harmfulness to the human body, and the durability of the manufacturing apparatus can be solved by the present invention. In addition, a separate process for treating spent sulfuric acid which causes environmental pollution is not necessary, and as a result, the manufacturing cost of aramid fiber can be drastically reduced.

Further, according to the present invention, by using a polymerization solution containing an aramid polymer having a broad molecular weight distribution, that is, a relatively high polydispersity index (PDI), by using an emissivity pro, It is possible to prevent radioactive degradation which may be caused. That is, since the radial dope of the present invention has radioactivity comparable to that of the radial dope containing a sulfuric acid solvent, the aramid fiber can be produced at a high radial rate.

Hereinafter, embodiments of the aramid fiber and the manufacturing method thereof according to the present invention will be described in detail.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. It will be apparent to those skilled in the art that variations are possible. Therefore, the present invention encompasses all changes and modifications that come within the scope of the invention as defined in the appended claims and equivalents thereof.

The aramid fiber of the present invention is a para-aramid fiber having a structure in which benzene rings are linearly connected through an amide group (CONH). Specifically, the aromatic polyamide of the aramid fiber of the present invention includes a repeating unit represented by the following formula (1).

[Formula 1]

Wherein R ₁ is —CN, —Cl, —SO ₃ H, or —CF ₃ , and Ar ₁ and Ar ₂ are each independently an aromatic hydrocarbon having 1 to 4 benzene rings. According to one embodiment of the present invention, R ₁ is -CN, and Ar ₁ and Ar ₂ are phenylene.

According to the present invention, the aromatic polyamide has a relatively high polydispersity index (PDI) of 2.4 to 3.0. That is, since the aromatic polyamide has a broad molecular weight distribution, the aramid fiber of the present invention can be produced at a high spinning speed.

The polydispersity index of an aromatic polyamide in an aramid fiber is measured by a light scattering method under the following conditions. Specifically, the polydispersity index based on the difference in light scattering degree between the reference solvent and the sample solution is automatically calculated by the following measuring apparatus.

1) Measuring device: Optilas T-Rex (DynaPro NanoStar)

2) Wavelength of light source: 658 nm

3) Reference solvent: The reference solvent is prepared by using an inorganic salt and an organic solvent which were respectively used for polymerization of aromatic polyamide. The content of the inorganic salt in the reference solvent is 3% by weight.

4) Sample solution: A sample solution was prepared by dissolving 0.5 wt% of aramid fiber in the reference solvent.

The aromatic polyamide may be a homopolymer having only the repeating unit of the above formula (1). Alternatively, the aromatic polyamide may be a copolymer further having a repeating unit represented by the following formula (2).

[Formula 2]

Here, Ar ₁ and Ar ₂ are each independently aromatic hydrocarbons having 1 to 4 benzene rings. According to one embodiment of the present invention, Ar ₁ and Ar ₂ are phenylene.

Hereinafter, a method for producing the aramid fiber of the present invention will be described in detail.

Preparation of Aromatic Polyamide Polymerization Solution

First, inorganic salts are dissolved in an organic solvent.

As the organic solvent, an amide organic solvent, a urea organic solvent, or a mixed organic solvent thereof may be used. Specific examples thereof include N-methyl-2-pyrrolidone (NMP) and N, N-dimethylacetamide. (DMAc), hexamethylphosphoramide (HMPA), N, N, N ', N'-tetramethyl urea (TMU), N, N-dimethylformamide (DMF), or mixtures thereof.

The inorganic salt is added in order to increase the degree of polymerization of the aromatic polyamide. Specific examples thereof include alkali metal halides such as CaCl ₂ , LiCl, NaCl, KCl, LiBr and KBr, or alkaline earth metal halides. These inorganic salts may be added singly or in the form of a mixture of two or more.

Since the inorganic salt has poor solubility in an organic solvent, according to an embodiment of the present invention, water is added to completely dissolve the inorganic salt, and thereafter, the water is removed through a dehydration process.

Inorganic salts function to increase the degree of polymerization of aromatic polyamides produced by the polymerization of aromatic diamines and aromatic dieside halides in organic solvents.

According to the conventional method, the amount of the inorganic salt added to the organic solvent was 6% by weight or more of the solution. That is, in the conventional method, since a sufficient number of inorganic salts functioning to increase the degree of polymerization of aromatic polyamides are used, the aromatic polyamides produced have a high intrinsic viscosity (IV) of greater than 5.0 and have a solid form such as bread crumbs. Have Since the aromatic polyamide would be dissolved in a sulfuric acid solvent to prepare a spinning dope, even if the intrinsic viscosity of the aromatic polyamide polymer exceeded 5.0, there was no problem in the spinning process.

However, in the present invention in which the polymerization solution is spun directly without using a sulfuric acid solvent, the intrinsic viscosity of the aromatic polyamide should not exceed 5.0. Therefore, according to the present invention, the amount of the inorganic salt dissolved in the organic solvent should be 5% by weight or less of the solution. For example, according to one embodiment of the present invention, 2 to 5% by weight of CaCl ₂ is dissolved in an NMP organic solvent. Then, immediately after dissolving CaCl ₂ in the organic solvent, a dehydration process is performed so that the moisture of the organic solvent is 120 ppm or less.

Then, unsubstituted from the group consisting of para-phenylenediamine, 4,4'-diaminodiphenyl, 2,6-naphthalenediamine, 1,5-naphthalenediamine, and 4,4'-diaminobenzanilide A non-substituted aromatic diamine is dissolved in the organic solvent to which the inorganic salt is added. At the same time, a substituted aromatic diamine in which the hydrogen of the benzene ring of the aromatic diamine is substituted with -CN, -Cl, -SO ₃ H, or -CF ₃ is dissolved in the organic solvent to which the inorganic salt is added . The molar ratio of the substituted aromatic diamine to the unsubstituted aromatic diamine dissolved in the organic solvent containing the inorganic salt is from 9: 1 to 1: 9.

According to one embodiment of the present invention, a mixture of cyano-p-phenylenediamine and para-phenylenediamine in an NMP organic solvent to which CaCl ₂ is added at a molar ratio of 9: 1 to 1: 9 Dissolve.

When both the unsubstituted aromatic diamine and the substituted aromatic diamine are dissolved in the organic solvent, the aromatic polyamide of the copolymer can be finally obtained. Alternatively, in order to obtain an aromatic polyamide having a homopolymer, only the substituted aromatic diamine can be dissolved in an organic solvent.

Next, an aromatic diacid halide is added to the organic solvent at least in the same molar amount as the aromatic diamine in order to obtain a polymerization solution containing an aromatic polyamide. The aromatic dieside halide is terephthaloyl dichloride, 4,4'-benzoyl dichloride, 2,6-naphthalenedicarboxylic acid dichloride or 1,5-naphthalenedicarboxylic acid dichloride. According to one embodiment of the invention, the aromatic dieside halide is terephthaloyl dichloride.

In the conventional method of producing radial dope using a sulfuric acid solvent, the unsubstituted aromatic diamine and the aromatic diacid halide are polymerized into an aromatic polyamide. At this time, polymerization reaction proceeds rapidly at high speed with heat generation and solidification becomes fast, so it is difficult to obtain a high molecular weight aromatic polyamide having a long molecular chain. In order to solve this problem, in the conventional method, an aromatic diacid halide was added in two divided portions. However, when the final polymerization is carried out after the prepolymerization, a high molecular weight aromatic polyamide can be obtained, but a molecular weight distribution of the aromatic polyamide tends to be narrowed.

Generally, a narrow molecular weight distribution causes a radioactive degradation, resulting in lower productivity due to the low spinning rate. However, due to the high solubility of the polymer in the sulfuric acid solvent, the aramid fiber could be produced at a high spinning rate despite the narrow molecular weight distribution of the polymer.

In the case of the present invention which does not use a sulfuric acid solvent, since the solubility of the aromatic polyamide in the polymerization solution is relatively low, the molecular weight distribution of the aromatic polyamide has a great influence on the radiation and the spinning speed. Therefore, measures for widening the molecular weight distribution of the aromatic polyamide are required.

According to the present invention, an aromatic diacid halide is added to an organic solvent at least in the same molar amount as an aromatic diamine to produce an aromatic polyamide immediately without a prepolymerization step. The aromatic polyamide thus produced has a relatively high polydispersity index (PDI) of 2.4 to 3.0. Thanks to the broad molecular weight distribution of the aromatic polyamides, the polymerization solution can be radiated at a high rate.

That is, according to the present invention, by using the polymerization solution containing an aramid polymer having a relatively high polydispersity index as an emissivity pro- ducer, it is possible to prevent radioactivity degradation caused by not using a sulfuric acid solvent. Since the radial dope of the present invention has radioactivity comparable to that of the radial dope containing a sulfuric acid solvent, the aramid fiber can be produced at a high radial rate.

On the other hand, since the aromatic diamine used in the present invention contains an aromatic diamine having a substituent, the reactivity with the aromatic diacid halide is relatively low. Therefore, in the present invention, the polymerization reaction proceeds at a relatively slow rate and the solidification occurs later. As a result, a high molecular weight aromatic polyamide having a long molecular chain can be obtained without going through the prepolymerization step.

The aromatic polyamide of the present invention obtained by the polymerization process includes a repeating unit represented by the following formula (1).

[Formula 1]

Wherein R ₁ is —CN, —Cl, —SO ₃ H, or —CF ₃ , and Ar ₁ and Ar ₂ are each independently an aromatic hydrocarbon having 1 to 4 benzene rings.

According to an embodiment of the present invention, R ₁ is —CN, and Ar ₁ and Ar ₂ are phenylene.

If both the unsubstituted aromatic diamine and the substituted aromatic diamine are dissolved in the organic solvent, the aromatic polyamide of the copolymer further containing the repeating unit represented by the following formula (2) is obtained in addition to the repeating unit represented by the above formula (1).

[Formula 2]

Here, Ar ₁ and Ar ₂ are each independently aromatic hydrocarbons having 1 to 4 benzene rings. According to one embodiment of the present invention, Ar ₁ and Ar ₂ are phenylene.

Subsequently, the acid (HCl) generated during the polymerization reaction is neutralized using an alkali compound. The alkali compound for neutralization is selected from the group consisting of alkali metals, carbonates of alkaline earth metals, hydrides of alkaline earth metals, hydroxides of alkaline earth metals, or oxides of alkaline earth metals. Specifically, the alkali compound is NaOH, Li ₂ CO ₃ , CaCO ₃ , LiH, CaH ₂ , LiOH, Ca (OH) ₂ , Li ₂ O or CaO.

According to one embodiment of the present invention, for the neutralization process, CaO equivalent to the acid (HCl) produced by the polymerization reaction is added to the polymerization solution. At the same time, water generated by the neutralization process is removed from the polymerization solution using a vacuum. As the intrinsic viscosity of the aromatic polyamide is increased to 5.0 or more by CaCl ₂ generated together with water in the neutralization with CaO, a polymer solution in which the polymer is uniformly dissolved in an organic solvent is obtained.

Then, the amount of the organic solvent in the polymerization solution may be adjusted so that the concentration of the aromatic polyamide in the polymerization solution is 10 to 20% by weight. If the concentration of the aromatic polyamide in the polymerization solution is out of the above range, the spinning process does not proceed smoothly, the productivity is lowered and the produced aramid fibers do not have satisfactory physical properties.

The polymerization solution prepared as above can be used directly as a spinning dope. That is, according to the present invention, separate processes required in the conventional process to obtain a solid aromatic polyamide, that is, extraction, washing, grinding and drying processes after the polymerization process can be omitted, as well as spinning dope production. In order to dissolve the solid aromatic polyamide in a sulfuric acid solvent may also be omitted.

Therefore, according to the present invention, the productivity can be greatly improved as the polymerization process and the spinning process are carried out simultaneously in the same apparatus, and the complexity of the manufacturing process due to the use of the sulfuric acid solvent, the harmfulness to the human body, and the manufacturing apparatus Problems such as deterioration of durability can be solved. In addition, since aramid fibers can be produced without using a sulfuric acid solvent that causes environmental pollution, a separate process for treating waste sulfuric acid is not necessary, and as a result, manufacturing cost of aramid fibers can be drastically reduced.

Using the polymerization solution Aramid  Manufacture of fibers

The polymerization solution in which the aromatic polyamide is uniformly dissolved in the organic solvent is extruded through a spinneret. The extruded polymerization solution is solidified while passing through a coagulation liquid in a coagulation bath through an air gap to form a filament.

The spinneret has a plurality of capillaries having a diameter of 0.1 mm or less. If the diameter of the capillary formed in the spinneret exceeds 0.1 mm, the molecular orientation of the resulting filament is poor, resulting in a decrease in the strength of the filament.

The air gap may be mainly an air layer or an inert gas layer, the length of the air gap is 0.1 to 15 cm is preferable for improving the physical properties of the filament is produced.

According to the present invention, in addition to water, the coagulating solution may further contain an alcohol such as ethylene glycol and glycerol. The coagulating solution is maintained at a high temperature of 10 to 90 캜.

Subsequently, the filament obtained through the coagulation step is washed with water or a mixed solution of water and an alkaline solution.

Then, a drying process is performed to adjust the moisture content remaining in the filament. The drying process may control the time for which the filament is in contact with the heated drying roll, or the moisture content of the filament by adjusting the temperature of the drying roll. The drying rolls are heated by some means, and the drying rolls are preferably at least partly surrounded by heat blocking means in order to prevent excessive heat from being released from the heated rolls and thereby causing heat loss.

Optionally, a heat treatment process may be performed on the dried filaments.

Subsequently, the filament having been dried and heat treated is wound around the branch pipe.

On the other hand, during the spinning process described above, the stretching step of increasing the filament is performed. Since the filament containing the copolymer has relatively low crystallinity, elongation may be high and physical properties such as strength and elastic modulus may be deteriorated. Therefore, the stretching process increases the crystallinity of the filament to improve the strength and elastic modulus of the filament. By controlling the conditions of the stretching process, the elongation of the filament to be produced can be adjusted in various ways depending on the application.

The filament may be adjusted in the draw ratio according to the content and use of the comonomer, the draw ratio may be adjusted in the range of 2 to 13 times. That is, when the content and spinning rate of the comonomer, for example, substituted aromatic diamine, is low, the draw ratio may be set high, and in the reverse case, the draw ratio may be set low. Accordingly, the draw ratio can be properly adjusted within the range of 2 to 13 times in accordance with the content of the comonomer and the spinning speed.

The stretching process may include a wet stretching process. The wet stretching step may be carried out in a coagulating liquid set in a temperature range of 40 to 90 占 폚.

Optionally, the stretching process may include a dry stretching process. The dry drawing process may be performed between the coagulation process and the winding process. That is, the dry drawing process may be performed before winding the filament solidified to the branch pipe to the extent that it can maintain a predetermined shape. For example, the dry drawing process may be performed in a drying process and / or a heat treatment process.

The above-mentioned key drawing process can be performed within a temperature range of 150 to 300 ° C. In the case of solidified filaments, the binding force between the molecular chains is relatively strong, and the fluidity of the molecular chain is relatively poor. Accordingly, the key drawing process for the coagulated filaments is performed at a relatively high temperature of 150 캜 or higher. On the other hand, when the temperature of the film drawing process exceeds 300 ° C, the flowability of the molecular chains increases more than necessary, which may make process control difficult.

Optionally, the stretching process may be performed through two stages of stretching, including both wet stretching and dry stretching. Through such two-stage stretching, the stability of the process can be improved by preventing sudden changes in molecular structure.

Hereinafter, the present invention will be described in detail with reference to examples and comparative examples. It is to be understood, however, that the following examples are intended to assist the understanding of the present invention, and the scope of the present invention is not limited thereby.

Example

An N-methyl-2-pyrrolidone (NMP) organic solvent containing 3% by weight of CaCl ₂ was placed in a reactor under a nitrogen atmosphere, and 50 mol% of p-phenylenediamine and cyano-para- 50 mol% of phenylenediamine (cyano-p-phenylenediamine) was added to the reactor and dissolved to prepare a mixed solution.

Then, 100 mol% of terephthaloyl dichloride was added to the reactor containing the mixed solution to obtain a polymerization solution containing the aramid polymer.

Subsequently, CaO, an alkali compound, was added to the polymerization solution to neutralize the hydrochloric acid generated during the polymerization reaction and to remove water produced by vacuum.

Subsequently, the polymerization solution containing the aramid polymer was heated and the amount of the organic solvent was adjusted to adjust the concentration of the aramid polymer to 16% by weight.

Subsequently, the polymer solution was extruded through a spinneret and then passed through an air gap and a coagulant solution, thereby forming a multifilament having a linear density of 3,000 denier. The pressure in the spinning pack was 2,800 psi and the spinning speed was 600 mpm (meter per minuite).

Then, the multifilament was washed with water, and the washed multifilament was dried and drawn on a drying roller set at a temperature of 150 ° C. The drawn multifilament was heat-treated at 250 ° C. and wound up to produce an aramid fiber.

Comparative example  One

An N-methyl-2-pyrrolidone (NMP) organic solvent containing 3% by weight of CaCl ₂ was placed in a reactor under a nitrogen atmosphere, and 50 mol% of para-phenylenediamine and 50 mol of cyanopara- % Were added to the reactor and dissolved to prepare a mixed solution.

40 mol% of terephthaloyl dichloride was added to the mixed solution to prepare a prepolymer, and 60 mol% of terephthaloyl dichloride was added to the reactor containing the prepolymer to obtain a polymerization solution.

Subsequently, CaO, an alkali compound, was added to the polymerization solution to neutralize the hydrochloric acid generated during the polymerization reaction and to remove water produced by vacuum.

Subsequently, the polymerization solution containing the aramid polymer was heated and the amount of the organic solvent was adjusted to adjust the concentration of the aramid polymer to 16% by weight.

Subsequently, the polymer solution was extruded through a spinneret and then passed through an air gap and a coagulant solution, thereby forming a multifilament having a linear density of 3,000 denier. The pressure of the spinning pack was 2,300 psi and the spinning speed was 500 mpm.

Then, the multifilament was washed with water, and the washed multifilament was dried and drawn on a drying roller set at a temperature of 150 ° C. The drawn multifilament was heat-treated at 250 ° C. and wound up to produce an aramid fiber.

Comparative example  2

After the polymerization solution was prepared in the same manner as in Comparative Example 1, the polymerization solution was extruded through spinneret under the same conditions as in Example 1 described above (pressure of spinning pack: 2,800 psi, spinning speed: 600 mpm). However, damage to the spinneret occurred. If the degree of damage (%) of the spinneret defined as the ratio of the area after deformation to the original area is over 102%, it becomes impossible to use. In this comparative example, the spinneret's damage degree was 105.2%.

The polydispersity index (PDI), tensile strength and elongation of the aramid fibers obtained by the above Examples and Comparative Examples were measured by the following methods, respectively, and the results are shown in Table 1.

Aramid  Of aromatic polyamide in fiber Dispersed  Indices( PDI )

The polydispersity index of the aromatic polyamide in the aramid fiber was measured by the light scattering method under the following conditions. Specifically, the polydispersity index based on the difference in the degree of light scattering between the reference solvent and the sample solution was automatically calculated by the following measuring apparatus.

1) Measuring device: Optilas T-Rex (DynaPro NanoStar)

2) Wavelength of light source: 658 nm

3) Reference solvent: N-methyl-2-pyrrolidone (NMP) with 3% by weight of CaCl ₂ added in an organic solvent

4) Sample solution: A sample solution was prepared by dissolving 0.5 wt% of aramid fiber in the reference solvent.

Aramid  Tensile strength and elongation of fiber

The tensile strength and elongation of the aramid fibers were measured by tensile strength and elongation at the breaking point after stretching until a sample of 25 cm in length was broken in an Instron Tester (Instron Engineering Corp., Canton, Mass.) According to ASTM D885 The above process was tested five or more times, and the average value was obtained. At this time, the tensile speed was 300 mm / min, and the initial load was fineness × 1/30 g.

division The polydispersity index (PDI) Tensile strength (g / d) Shinto (%) Example 2.5 22 3.4 Comparative Example 1 2.2 23 3.5 Comparative Example 2 Damage to spinning detention occurred

Claims (15)

An aromatic polyamide having a repeating unit represented by the following formula (1)
[Formula 1]

Wherein R ₁ is —CN, —Cl, —SO ₃ H, or —CF ₃ , and Ar ₁ and Ar ₂ are each independently an aromatic hydrocarbon having 1 to 4 benzene rings;
Wherein the aromatic polyamide has a polydispersity index (PDI) of 2.4 to 3.0. The method of claim 1,
Wherein R ₁ is —CN, and Ar ₁ and Ar ₂ are phenylene. The method of claim 1,
Wherein the aromatic polyamide is a homopolymer having only the repeating unit of the formula (1). The method of claim 1,
Wherein the aromatic polyamide is a copolymer having a repeating unit represented by the following formula (2): < EMI ID =
(2)

Wherein Ar ₁ and Ar ₂ are each independently aromatic hydrocarbons having 1 to 4 benzene rings. 5. The method of claim 4,
Wherein R ₁ is —CN, and Ar ₁ and Ar ₂ of Formula 1 and Formula ₂ are phenylene. Dissolving in an organic solvent an aromatic diamine comprising a substituted aromatic diamine wherein the hydrogen of the benzene ring is substituted with -CN, -Cl, -SO ₃ H, or -CF ₃ ;
Then, adding aromatic diacid halide to the organic solvent at least in the same molar amount as the aromatic diamine to obtain a polymerization solution containing an aromatic polyamide;
Extruding the polymer solution through a spinneret; And
And allowing the extruded polymer solution to pass through the coagulation liquid to form a filament. The method according to claim 6,
Wherein the aromatic diamine dissolved in the organic solvent contains only the substituted aromatic diamine. The method of claim 7, wherein
Wherein said substituted aromatic diamine is cyano-p-phenylenediamine,
Wherein said aromatic diacid halide is terephthaloyl dichloride. ≪ RTI ID = 0.0 > 11. < / RTI > The method according to claim 6,
Wherein the aromatic diamine dissolved in the organic solvent further comprises an unsubstituted aromatic diamine. 10. The method of claim 9,
Wherein the molar ratio of the substituted aromatic diamine and the unsubstituted aromatic diamine dissolved in the organic solvent is 1: 9 to 9: 1. 10. The method of claim 9,
Wherein said substituted aromatic diamine and said unsubstituted aromatic diamine are cyano-para-phenylenediamine and para-phenylenediamine, respectively,
Wherein said aromatic diacid halide is terephthaloyl dichloride. ≪ RTI ID = 0.0 > 11. < / RTI > 10. The method of claim 9,
Further comprising the step of dissolving 2 to 5% by weight of CaCl ₂ in the organic solvent before the substituted aromatic diamine and the unsubstituted aromatic diamine are dissolved in the organic solvent. The method of claim 12,
Further comprising the step of dehydrating the organic solvent so that the water content of the organic solvent is 120 ppm or less immediately after dissolving the CaCl ₂ in the organic solvent. The method according to claim 6,
Further comprising the step of adding CaO to the polymerization solution to neutralize the HCl generated in the polymerization process before the polymerization solution is extruded. 15. The method of claim 14,
Further comprising the step of adding the CaO to the polymerization solution and removing water from the polymerization solution.