KR101561544B1 - Method of manufacturing conductive aramid fiber and conductive aramid fiber manufactured thereby - Google Patents

Abstract

The present invention relates to an emulsion composition in which graphite is added to an emulsion and ultrasonic waves are generated in the emulsion to form graphite as graphene to prepare an emulsion composition in which graphene is dispersed, To produce conductive aramid fibers.
Wherein the coating amount of the emulsion composition is 0.01 to 10% by weight based on the total weight of the aramid fibers coated with the emulsion composition, the content of graphene in the emulsion composition is 0.01 to 30% by weight, It is preferably an ether compound.
In the present invention, since graphene is formed from graphite by injecting graphite into an emulsion instead of graphene, a separate graphene production process can be omitted, thereby simplifying the process and reducing manufacturing cost.
In addition, the present invention improves the conductivity of the aramid fiber even when a small amount of graphene is used, and the amount of graphene added is small, so that the fiber defects due to the addition of graphene can be minimized and the mechanical properties such as the strength of the conductive aramid fiber Can be prevented.
Further, the present invention can improve the dispersibility of graphene in an emulsion composition by using an emulsion excellent in interaction with graphene.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for producing a conductive aramid fiber and a conductive aramid fiber produced by the method,

The present invention relates to a method for producing conductive aramid fibers and conductive aramid fibers produced therefrom, and more particularly, to a method for producing conductive aramid fibers by preparing an emulsion composition in which graphene is dispersed by a simple process and a low cost, The present invention relates to a method for producing a conductive aramid fiber capable of improving electrical conductivity without degrading the mechanical properties of the aramid fiber, and a conductive aramid fiber produced by the method.

The aromatic polyamide fibers commonly referred to as aramid fibers are prepared by polymerizing an aromatic diamine and an aromatic diacid chloride in a polymerization solvent to prepare an aromatic polyamide polymer and then dissolving the aromatic polyamide polymer in a concentrated sulfuric acid solvent to prepare a radial dope, The radiation dope is radiated through a spinneret, and then the radiation is solidified to produce a filament.

Such aramid fibers include para-aramid fibers having a structure in which benzene rings are linearly connected through an amide group (CONH), and meta-based aramid fibers not having such a structure. Para-aramid fibers have excellent properties such as high strength, high elasticity and low shrinkage. They have a strong strength enough to lift 2 tons of automobile with a thin thread of 5mm thickness, Of-the-art industry.

On the other hand, there is a demand for aramid fibers having superior mechanical properties and good electrical conductivity for special applications.

As a conventional technique for imparting conductivity to aramid fibers, U.S. Patent No. 5,853,640 discloses a method for producing conductive aramid fibers by adding and dispersing carbon nanotubes in a radial dope in which an aramid polymer is dissolved in sulfuric acid, followed by spinning the carbon nanotubes.

In the case of the method of mixing the conductive additive or the conductive polymer with the aramid fiber as in the above-described prior art, it is necessary to mix the excess conductive additive or the conductive polymer with the aramid fiber in order to obtain the desired conductivity. Mechanical properties such as strength are deteriorated.

As another conventional technique, Korean Patent Laid-Open No. 10-2012-0063853 discloses a method of preparing an aramid-graphene composite by mixing a solution of an aramid-exclusive polymer with graphene. However, There is a problem in that the manufacturing process is very complicated and the manufacturing cost is also increased because there is a step of separately preparing these components and then mixing them again.

It is an object of the present invention to provide a method for manufacturing aramid fibers with a simpler process and a lower cost, which can significantly improve electrical conductivity without deteriorating mechanical properties such as strength.

In order to achieve the above object, the present invention provides an emulsion composition in which graphite is dispersed in graphene by injecting graphite into an emulsion and then generating ultrasonic waves in the emulsion to form graphite as graphene, thereby coating the surface of the aramid fiber.

Further, the present invention improves the dispersibility of graphene in an emulsion composition by using an emulsion excellent in interaction with graphene and generating ultrasonic waves in the emulsion.

In the present invention, since graphene is formed from graphite by injecting graphite into an emulsion instead of graphene, a separate graphene production process can be omitted, thereby simplifying the process and reducing manufacturing cost.

Further, the present invention improves the conductivity of the aramid fibers even when a small amount of graphene is used, and the amount of graphene added is small, so that the fiber defects due to the addition of graphene can be minimized, so that the mechanical properties such as the strength of the conductive aramid fiber .

Further, the present invention can improve the dispersibility of graphene in an emulsion composition by using an emulsion excellent in interaction with graphene.

Hereinafter, the present invention will be described in detail.

The present invention relates to a method for producing an emulsion composition which comprises injecting graphite into an emulsion and then generating ultrasonic waves in the emulsion to make the graphite into graphene to prepare an emulsion composition in which graphene is dispersed, And coating the composition.

In the present invention, since graphene is formed from graphite by injecting graphite into an emulsion instead of graphene, a separate graphene production process can be omitted, thereby simplifying the process and reducing manufacturing cost.

Graphene is a material that forms a two-dimensional planar structure in which a carbon atom is connected in a hexagonal honeycomb shape. It also includes graphene as well as pure graphene.

At this time, it is preferable that the content of graphene in the emulsion composition is 0.01 to 30 wt%, and the coating amount of the emulsion composition is 0.01 to 10 wt% with respect to the total weight of the aramid fiber coated with the emulsion composition.

When the content of graphene in the emulsion composition is less than 0.01% by weight, the effect of improving the conductivity is insignificant. When the content of the graphene exceeds 30% by weight, uniform coating of the aramid fibers is difficult due to the phase separation of graphene.

The emulsion constituting the emulsion composition is an ether compound or an ester compound, preferably an ether compound, for improving the dispersibility of the graphene in the emulsion composition.

A conventional method of applying an ordinary emulsion to the surface of the aramid fiber radiated during the process of spinning the aramid fiber may be used to coat the emulsion composition in which graphene is dispersed or the surface of the aramid fiber that has undergone the spinning / An emulsion feed roller or the like may be used to coat the emulsion composition in which graphene is dispersed.

In the present invention, since the emulsion composition in which graphene is dispersed is coated only on the surface of the aramid fiber, even when a small amount of graphene is used at the time of coating, the electrical conductivity can be greatly improved and defects due to excessive use of graphene can be prevented Thereby minimizing deterioration of mechanical properties such as strength.

In the present invention, since graphene is formed from graphite by injecting graphite into an emulsion instead of graphene, a separate graphene production process can be omitted, thereby simplifying the process and reducing manufacturing cost.

The conductive aramid fibers produced according to the method of the present invention described above have an electrical conductivity of 10 ² to 10 ⁷ Ω and a strength of 23 to 26 g / d.

A preferred embodiment of the present invention will be described in more detail. First, a mixed solution is prepared by dissolving an aromatic diamine in a polymerization solvent, and then a predetermined amount of aromatic diacid halide is added to the mixed solution to perform a prepolymerization step Subsequently, the mixture is stirred at 0 to 30 DEG C to add the remaining amount of aromatic diacid halide to the mixed solution, and the mixture is polymerized to prepare an aramid polymer.

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

The inorganic salt is added in order to increase the polymerization degree of the aramid polymer. Specific examples thereof include alkali metal halides such as CaCl ₂ , LiCl, NaCl, KCl, LiBr and KBr, or alkaline earth metal halides. May be added alone or in the form of a mixture of two or more. As the addition amount of the inorganic salt increases, the degree of polymerization of the aramid polymer increases. However, since an inorganic salt which does not dissolve when the inorganic salt is added in an excessive amount may exist, the inorganic salt may be present in an amount of not more than 10% .

Specific examples of the aromatic diamine include para-phenylenediamine, 4,4'-diaminobiphenyl, 2,6-naphthalenediamine, 1,5-naphthalenediamine or 4,4'-diaminobenzanilide However, the present invention is not limited thereto.

Polymerization of an aromatic diamine and an aromatic diacid halide proceeds at a rapid rate with the exothermic reaction. When the polymerization rate is increased as described above, there arises a problem that the difference in degree of polymerization between the finally obtained polymers increases. More specifically, since the polymerization reaction does not proceed at the same time in the entire mixed solution, the polymer in which the polymerization reaction is initiated first rapidly undergoes a polymerization reaction to form a long molecular chain, The shorter the molecular chain, the faster the polymerization rate becomes. As described above, when the difference in degree of polymerization between the finally obtained polymers becomes large, the physical property deviation becomes large, which makes it difficult to realize the desired characteristics.

Thus, through the prepolymerization process, a polymer having a molecular chain of a predetermined length is formed in advance, and then a polymerization process is performed to minimize the difference in degree of polymerization between the finally obtained polymers.

Specific examples of the aromatic diacid halide include terephthaloyl dichloride, 4,4'-benzoyl dichloride, 2,6-naphthalene dicarboxylic acid dichloride and 1,5-naphthalene dicarboxylic acid dichloride, But is not limited thereto.

Since the aromatic diacid halide reacts with the aromatic diamine in a 1: 1 molar ratio in the preparation of the aramid polymer, the aromatic diamine and the aromatic diacid halide can be added at the same molar ratio.

It is preferable to adjust the amount of the aromatic diamine and the di-halide halide so that the concentration of the final polymer in the entire polymerization solution is about 5 to 20% by weight after completion of the polymerization process. When the aromatic diamine and the di-halide halide are added so that the concentration of the final polymer is less than 5% by weight, the polymerization rate is lowered and the reaction is required to be carried out for a long period of time, resulting in poor economical efficiency. And di-sic halide are added, the polymerization reaction can not proceed smoothly and the intrinsic viscosity of the polymer can not be improved.

Specific examples of the aramid polymer obtained by the polymerization process include poly (paraphenylene terephthalamide: PPD-T), poly (4,4'-benzanilide terephthalamide), poly (paraphenylene- Biphenylene-dicarboxylic acid amide) or poly (paraphenylene-2,6-naphthalenedicarboxylic acid amide).

On the other hand, when the polymerization reaction proceeds, an acid such as hydrochloric acid is generated. Such an acid causes problems such as corrosion of the polymerization apparatus. Therefore, an inorganic alkali compound or an organic alkali compound is added during the polymerization reaction or after the polymerization reaction It is preferable to neutralize the acid.

At this time, since the aramid polymer obtained through the polymerization reaction exists in the form of bread crumbs, the flowability of the aramid polymer solution is poor. Therefore, in order to improve the flowability, it is preferable to add water to the aromatic polyamide solution to prepare a slurry, and then carry out the subsequent step. For this purpose, water is added to the aromatic polyamide solution in an aromatic polyamide solution, The process can be carried out.

The inorganic alkaline compound may be at least one selected from the group consisting of alkaline metals such as NaOH, Li ₂ CO ₃ , CaCO ₃ , LiH, CaH ₂ , LiOH, Ca (OH) ₂ , Li ₂ O or CaO, carbonates of alkaline earth metals, hydrides of alkaline earth metals, Hydroxide, or an oxide of an alkaline earth metal.

Upon completion of the neutralization process, the aramid polymer is pulverized, the polymerization solvent is removed, and the polymer is dehydrated and dried to complete the production of the aramid polymer.

Next, an aramid polymer prepared by the above-described method is added to a sulfuric acid solution and dissolved to prepare a spinning dope.

The sulfuric acid solution may be a concentrated sulfuric acid solvent having a concentration of 97 to 100%. In place of the concentrated sulfuric acid, chlorosulfuric acid or fluorosulfuric acid may be used.

Next, the prepared spinning dope is passed through a spinneret and then coagulated by passing through an air gap and a coagulation bath in sequence, dried, and an emulsion feed roller is placed on the dried fiber surface And then coated with an emulsion composition containing 0.01 to 30% by weight of graphene dispersed therein, followed by winding to prepare conductive aramid fibers on the filament.

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples.

However, the scope of protection of the present invention is not limited to the following embodiments.

Example 1

After injecting graphite into the emulsion as an ether compound, ultrasonic waves were generated in the emulsion to make graphite as graphene to prepare an emulsion composition having 10 wt% of graphene dispersed therein.

Meanwhile, CaCl ₂ was added to N-methyl-2-pyrrolidone (NMP) to prepare a polymerization solvent, and para-phenylenediamine was dissolved in the polymerization solvent to prepare a mixed solution. Thereafter, while the above mixed solution was being stirred, terephthaloyl dichloride was added to the mixed solution in the same molar amount as the para-phenylenediamine in two portions to produce a poly (paraphenylene terephthalamide) polymer. Thereafter, water and NaOH were added to the polymerization solution containing the polymer to neutralize the acid, and then the polymer was pulverized. Thereafter, the polymerization solvent contained in the polymer was extracted by using water, and finally an aramid polymer was obtained through a dehydration and drying process.

Next, the aramid polymer prepared above was added to and dissolved in a sulfuric acid solution at a concentration of 99% to prepare a spinning dope.

Next, the prepared spinning dope is radiated through a spinneret, followed by successively coagulating the air gap and the coagulation tank and then drying. Thereafter, using the emulsion feed roller, the emulsion composition (the emulsion composition And 10 wt% of graphene was dispersed therein) was coated on the surface of the dried fiber and then wound to produce conductive aramid fiber.

The electrical conductivity and strength of the prepared conductive aramid fiber were measured and the results are shown in Table 1.

Example 2

After injecting graphite into an ester compound, an ultrasonic wave was generated in the emulsion to form graphite as graphene to prepare an emulsion composition having 15 wt% of graphene dispersed therein.

Meanwhile, CaCl ₂ was added to N-methyl-2-pyrrolidone (NMP) to prepare a polymerization solvent, and para-phenylenediamine was dissolved in the polymerization solvent to prepare a mixed solution. Thereafter, while the above mixed solution was being stirred, terephthaloyl dichloride was added to the mixed solution in the same molar amount as the para-phenylenediamine in two portions to produce a poly (paraphenylene terephthalamide) polymer. Thereafter, water and NaOH were added to the polymerization solution containing the polymer to neutralize the acid, and then the polymer was pulverized. Thereafter, the polymerization solvent contained in the polymer was extracted by using water, and finally an aramid polymer was obtained through a dehydration and drying process.

Next, the aramid polymer prepared above was added to and dissolved in a sulfuric acid solution at a concentration of 99% to prepare a spinning dope.

Next, the prepared radial dope was radiated through a spinneret, followed by coagulation, followed by air gap and coagulation tank, followed by drying and winding to produce an aramid fiber.

Next, the emulsion composition (having 15 wt% of graphene dispersed in the ester compound) was coated on the surface of the aramid fiber prepared above using the emulsion feed roller to form the conductive aramid fiber .

The electrical conductivity and strength of the prepared conductive aramid fiber were measured and the results are shown in Table 1.

Comparative Example 1

A mixed solvent was prepared by adding CaCl ₂ to N-methyl-2-pyrrolidone (NMP) to prepare a polymerization solvent and then dissolving para-phenylenediamine in the polymerization solvent. Thereafter, while the above mixed solution was being stirred, terephthaloyl dichloride was added to the mixed solution in the same molar amount as the para-phenylenediamine in two portions to produce a poly (paraphenylene terephthalamide) polymer. Thereafter, water and NaOH were added to the polymerization solution containing the polymer to neutralize the acid, and then the polymer was pulverized. Thereafter, the polymerization solvent contained in the polymer was extracted by using water, and finally an aramid polymer was obtained through a dehydration and drying process.

Next, the prepared aramid polymer and the carbon nanotube were dissolved in a 99% sulfuric acid solution to prepare a radiation doping.

At this time, the content of carbon nanotubes in the radial dope was made 35 wt% based on the weight of the aramid polymer.

Next, the spinning dope was spun through a spinneret, passed through an air cap, passed through a spinning tube, sprayed together with a coagulating solution through a spinning tube, and then dried to produce a conductive aramid fiber .

The electrical conductivity and strength of the prepared conductive aramid fiber were measured and the results are shown in Table 1.

Results of physical property evaluation division Electrical Conductivity (Ω) Strength (g / d) Example 1 10 ⁵ 25 Example 2 10 ⁶ 24 Comparative Example 1 10 ⁴ 21

The strength and electrical conductivity of the conductive aramid fiber in the present invention were measured by the following method.

Strength (g / d)

The strength of the aramid fiber was measured according to the ASTM D885 test method.

Specifically, the strength of the aramid fiber was determined by stretching until the aramid fiber length of 25 cm was broken in an Instron Engineering corp (Canton, Mass).

At this time, the tensile speed was set to 300 m / min, and the initial load was set to 1/130 g.

The intensity was determined by averaging the five samples after testing.

Electrical Conductivity (Ω)

Five strands of the fiber are taken over a length of 10 cm and spread evenly on the glass glass so that they do not overlap each other, and are fixed with Scotch tape, and conductive silver paste is spread on the fiber 5 strands at intervals of 10 mm therebetween. Electrical resistance was measured by contacting a probe of a precision electric resistance tester (Model 3244, Hioki Co. Ltd.).

Claims (6)

After injecting graphite into an emulsion, ultrasonic waves are generated in the emulsion to form graphite as graphene, and an emulsion composition in which graphene is dispersed is prepared. Then, an emulsion composition in which the graphene is dispersed is coated on the surface of the aramid fiber By weight based on the weight of the conductive aramid fiber. The method for producing conductive aramid fibers according to claim 1, wherein the coating amount of the emulsion composition is 0.01 to 10% by weight based on the total weight of the aramid fibers coated with the emulsion composition. The method for producing conductive aramid fibers according to claim 1, wherein the content of graphene in the emulsion composition is 0.01 to 30% by weight. The method for producing a conductive aramid fiber according to claim 1, wherein the emulsion forming the emulsion composition is one selected from an ester compound and an ether compound. The method of claim 1, wherein the graphene is graphene oxide. delete