KR101158826B1 - Manufacturing method for polyacrylonitrile-based carbon fiber comprising carbon nanotube improved dispersibility and interfacial adhesion, and the carbon fiber therefrom - Google Patents

Abstract

The present invention relates to a method for producing a polyacrylonitrile-based carbon fiber comprising carbon nanotubes having improved dispersibility and interfacial adhesion, and to carbon fibers prepared therefrom, and more particularly, to a carbon bonded to a functional group according to the present invention. Forming nanotubes, preparing a polyacrylonitrile-based carbon fiber precursor composition comprising the carbon nanotubes, spinning the composition to prepare precursor fibers, and heat treating and oxidizing the precursor fibers Method for producing a polyacrylonitrile-based carbon fiber comprising the step of; And it relates to a polyacrylonitrile-based carbon fiber produced by the above method.
In the method for producing a polyacrylonitrile-based carbon fiber according to the present invention, the dispersibility and interfacial adhesion to the polyacrylonitrile-based carbon fiber precursor composition are improved by using the carbon nanotubes having the functional groups as described above. Not only can this excellent carbon fiber be produced, but the functional group promotes the cyclization reaction of the carbon fiber precursor, so that a homopolymer without comonomer can be used as a raw material of the carbon fiber precursor, and the calorific value is reduced during the stabilization step. There is an advantage to produce a higher performance carbon fiber.

Description

MANUFACTURING METHOD FOR POLYACRYLONITRILE-BASED CARBON FIBER COMPRISING CARBON NANOTUBE IMPROVED DISPERSIBILITY AND INTERFACIAL ADHESION, AND THE CARBON FIBER THEREFROM}

The present invention relates to a method for producing a polyacrylonitrile-based carbon fiber and a carbon fiber produced therefrom.

Carbon fiber is lighter than steel and superior in strength, and is widely used in various fields such as automobile, aerospace, wind power, and sports.

Such carbon fibers are largely classified into polyacrylonitrile-based carbon fibers and pitch-based carbon fibers based on their precursors.

Among them, polyacrylonitrile-based carbon fibers are known to have excellent strength, and pitch-based carbon fibers have high elastic modulus. Until now, many researchers have been trying to develop high-performance carbon fibers that simultaneously improve the strength and elastic modulus of carbon fibers. However, there is no significant progress commercially.

In this regard, when carbon compounds such as carbon nanotubes, carbon black, and graphite are used as additives in the production of carbon fibers, it is expected that the strength and elastic modulus may be improved at the same time. It is expected that the ripple effect will be very large when the physical properties of carbon fiber precursors such as carbon fiber are used as a fiber reinforcing agent to improve physical properties.

However, since carbon nanotubes are hydrophobic in nature, they are aggregated together by van der Waals forces, and thus, their compatibility with solvents and polymer raw materials is very low. There is this.

Thus, many studies have been made to improve the dispersibility of carbon nanotubes, such as treating carbon nanotubes with an acid, but the compatibility with polyacrylonitrile dissolved in a polar solvent is still poor. There is an urgent need for improvement.

The present invention provides a method for producing a polyacrylonitrile-based carbon fiber having excellent strength and elastic modulus simultaneously using carbon nanotubes having improved dispersibility and interfacial adhesion to the polyacrylonitrile-based carbon fiber precursor composition.

The present invention also provides a carbon fiber produced according to the above method.

The present invention

Forming a carbon nanotube to which a functional group of Formula 1 is bonded;

Preparing a polyacrylonitrile-based carbon fiber precursor composition comprising the carbon nanotubes;

Spinning the composition to produce precursor fibers; And

Heat treating and oxidizing the precursor fibers

Method for producing a polyacrylonitrile-based carbon fiber containing

Provides:

[Formula 1]

In Formula 1,

One to three of R ₁ to R ₅ are a carboxylic acid group (-COOH), a sulfonic acid group (-SO ₃ H), or a nitrile group (-CN), and the rest are hydrogen groups (-H);

R ₆ is a chemical bond, an ester bond (-COO-), or an amide bond (-CONH-);

However, when R ₆ is an ester bond (-COO-) or an amide bond (-CONH-), one to three of R ₁ to R ₅ are carboxylic acid groups (-COOH), and the rest are hydrogen groups (-H )to be.

Here, the carbon nanotubes to which the functional groups are bonded may be 1 to 40 parts by weight based on 100 parts by weight of the carbon nanotubes.

In addition, the carbon nanotubes may have an average diameter of 1 to 100 nm and an average length of 0.1 to 50 μm.

In addition, the carbon fiber precursor composition includes 0.1 to 30 parts by weight of carbon nanotubes, 0.1 to 0.5 parts by weight of a polymerization initiator, and 400 to 600 parts by weight of an organic solvent, based on 100 parts by weight of the acrylonitrile monomer. The composition may be polymerized.

In this case, the polyacrylonitrile-based carbon fiber precursor composition is one selected from the group consisting of methyl acrylate, methyl methacrylate, acrylic acid, methacrylic acid, and itaconic acid based on 100 parts by weight of the acrylonitrile monomer. It may be a polymerized composition further comprising 1 to 15 parts by weight of the above components.

In addition, the carbon fiber precursor composition may include 0.1 to 30 parts by weight of the carbon nanotubes and 400 to 600 parts by weight of the organic solvent in which the functional group is bonded to 100 parts by weight of the polyacrylonitrile polymer.

In addition, the step of heat treatment and oxidation treatment of the precursor fiber may be performed by heat treatment the precursor fiber at 200 to 300 ℃ for 50 to 120 minutes, it is oxidized at 1200 to 1800 ℃.

According to the production method of the present invention, the mechanical properties of the polyacrylonitrile-based carbon fibers compared to the polyacrylonitrile-based carbon fibers not containing carbon nanotubes, the strength (strength) 0.5 to 2.0 GPa and modulus 50 To 200 GPa.

On the other hand, the present invention provides a polyacrylonitrile-based carbon fiber prepared by the above method and improved mechanical properties.

In the method for producing a polyacrylonitrile-based carbon fiber according to the present invention, the dispersibility and interfacial adhesion to the polyacrylonitrile-based carbon fiber precursor composition are improved by using the carbon nanotubes having the functional groups as described above. Not only can this excellent carbon fiber be produced, but the functional group promotes the cyclization reaction of the carbon fiber precursor, so that a homopolymer without comonomer can be used as a raw material of the carbon fiber precursor, and the calorific value is reduced during the stabilization step. There is an advantage to produce a higher performance carbon fiber.

1 is a graph showing Raman spectroscopy comparing carbon nanotubes before and after a functional group is bonded according to an embodiment of the present invention.
FIG. 2 is a graph showing the results of X-ray Photoelectron Spectroscopy (XPS) analysis on carbon nanotubes before and after the functional group is bonded according to an embodiment of the present invention.
Figure 3 is a graph showing a comparison of the results of TGA (Thermogravimetry Analysis) for the carbon nanotubes before and after the functional group is bonded according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings, a method for producing a polyacrylonitrile-based carbon fiber according to the present invention and a carbon fiber produced therefrom will be described.

The present inventors in the course of repeating the study on the polyacrylonitrile-based carbon fiber containing carbon nanotubes, when the carbon fiber is added to the carbon nanotubes bonded to the functional group according to the formula (1), carbon fiber precursor The dispersibility and interfacial adhesion of the carbon nanotubes to the composition can be improved to produce carbon fibers having excellent mechanical properties. In addition, the functional group promotes the cyclization reaction of the carbon fiber precursors. Homopolymer can be used, and it was confirmed that carbon fibers having excellent mechanical properties could be prepared, and thus completed the present invention.

Such the present invention, according to one embodiment,

Forming a carbon nanotube to which a functional group of Formula 1 is bonded;

Preparing a polyacrylonitrile-based carbon fiber precursor composition comprising the carbon nanotubes;

Spinning the composition to produce precursor fibers; And

Heat treating and oxidizing the precursor fibers

It provides a method for producing a polyacrylonitrile-based carbon fiber comprising:

[Formula 1]

In Formula 1,

One to three of R ₁ to R ₅ are a carboxylic acid group (-COOH), a sulfonic acid group (-SO ₃ H), or a nitrile group (-CN), and the rest are hydrogen groups (-H);

R ₆ is a chemical bond, an ester bond (-COO-), or an amide bond (-CONH-);

However, when R ₆ is an ester bond (-COO-) or an amide bond (-CONH-), one to three of R ₁ to R ₅ are carboxylic acid groups (-COOH), and the rest are hydrogen groups (-H )to be.

Hereinafter, each step that can be included in the method for producing a polyacrylonitrile-based carbon fiber according to the present invention will be described in more detail.

First, the manufacturing method according to an embodiment of the present invention may be performed to form a carbon nanotube to which a functional group of formula 1 is bonded:

[Formula 1]

In Formula 1,

One to three of R ₁ to R ₅ are a carboxylic acid group (-COOH), a sulfonic acid group (-SO ₃ H), or a nitrile group (-CN), and the rest are hydrogen groups (-H);

R ₆ is a chemical bond, an ester bond (-COO-), or an amide bond (-CONH-);

However, when R ₆ is an ester bond (-COO-) or an amide bond (-CONH-), one to three of R ₁ to R ₅ are carboxylic acid groups (-COOH), and the rest are hydrogen groups (-H )to be.

The forming of the carbon nanotubes to which the functional groups are bonded is a pretreatment step to evenly disperse the carbon nanotubes in the carbon fiber precursor composition and to further improve the interfacial adhesion between the carbon fiber precursor composition and the carbon nanotubes.

In addition, the functional group bonded to the carbon nanotubes in the step may also serve to promote the cyclization reaction of the carbon fiber precursor, homogeneous without comonomers such as itaconic acid as a raw material of the carbon fiber precursor composition The polymer can be used, and the heat released in the stabilization step can be reduced, thereby minimizing the trimming of the monofilament.

On the other hand, the step may be performed by i) a method of binding the functional group after the acid (carbon) carbon nanotube, or ii) a method of directly covalently bonding the functional group to the carbon nanotubes.

First of all, the method of iii) is performed by first treating a carbon nanotube with an acid to introduce a carboxylic acid group (-COOH), and then bonding a functional group to a position of the carboxylic acid group. (See Example 1 to be described later).

That is, when carried out by the method of iii), in formula 1, R ₆ is an ester bond (-COO-) or an amide bond (-CONH-); One to three of R ₁ to R ₅ are carboxylic acid groups (-COOH), and the rest are hydrogen groups (-H).

At this time, the compound of the formula (2) may be used to introduce the functional group as described above in the carbon nanotubes, preferably 3-amino benzoic acid, 4-amino benzoic acid , 3-amino phthalic acid, 4-amino phthalic acid, 4-amino isophthalic acid, 5-amino isophthalic acid , 3-hydroxy benzoic acid, 4-hydroxy benzoic acid, 3-hydroxy phthalic acid, 4-hydroxy phthalic acid acid), 4-hydroxy isophthalic acid, or 5-hydroxy isophthalic acid can be used:

[Formula 2]

In Chemical Formula 2

One to three of R ₁ to R ₅ are carboxylic acid groups (—COOH), and the rest are hydrogen groups (—H); Z is an amine group (-NH ₂ ) or a hydroxyl group (-OH).

Secondly, the forming of the carbon nanotubes to which the functional groups are bonded may be performed by ii) a method in which the functional group is directly covalently bonded to the carbon nanotubes (see Example 2 to be described later). In this case, in Chemical Formula 1, R ₆ is a chemical bond; One to three of R ₁ to R ₅ are a carboxylic acid group (-COOH), a sulfonic acid group (-SO ₃ H), or a nitrile group (-CN), and the rest are hydrogen groups (-H).

At this time, the compound of the following formula (3) can be used for the introduction of the functional group, preferably benzoic acid (benzoic acid), phthalic acid (phthalic acid), isophthalic acid (isophthalic acid); Benzenesulfonic acid, benzene-1,2-disulfonic acid, benzene-1,3-disulfonic acid; Benzonitrile, benzene-1,2-dicarbonitrile, benzene-1,3-dicarbonitrile, or benzene-1,2 , 3-tricarbonitrile (benzene-1,2,3-tricarbonitrile) can be used.

(3)

In Chemical Formula 3, _one to three of R ₁ to R ₅ are a carboxylic acid group (-COOH), a sulfonic acid group (-SO ₃ H), or a nitrile group (-CN), and the rest are hydrogen groups (-H )to be.

In particular, when the ii) functional group is directly covalently bonded to the carbon nanotubes as described above, the functional group is directly processed in one step without undergoing an acid treatment step for the carbon nanotubes as compared to the case of performing the above-described method iii). Since it is covalently bonded, there is an advantage that can lower the manufacturing cost and simplify the manufacturing process is more desirable and can be.

Meanwhile, the carbon nanotubes in the step may be single-walled nanotubes (SWNT), multi-walled nanotubes (MWNT), or a mixture thereof.

In this case, the carbon nanotubes may have an average diameter of 1 to 100 nm, preferably 5 to 20 nm. That is, the average diameter is preferably 2 nm or more in order to express the agglomeration improvement effect of carbon nanotubes, and the diameter is larger than necessary to prevent the mechanical / electrical properties of the carbon nanotubes from deteriorating. It is preferable that an average diameter is 100 nm or less.

In addition, the carbon nanotubes preferably have an average length of 0.1 to 50 ㎛. That is, the average length of the carbon nanotubes is preferably 0.1 ㎛ or more in order to express the mechanical properties improvement effect of the carbon fiber, the length is longer than necessary, so that dispersibility is reduced by entanglement of carbon nanotubes. In order to prevent that, the average length is preferably 50 µm or less.

In addition, the step of forming the carbon nanotubes to which the functional group is bonded is 1 to 40 parts by weight, preferably 5 to 30 parts by weight, more preferably 5 to 100 parts by weight of the carbon nanotubes bonded to the functional group To 20 parts by weight. That is, the content of the functional group may be variously adjusted according to the number of walls of the carbon nanotubes, in consideration of the dispersibility and the interface adhesion improving effect required for the carbon nanotubes, so that the functional group of the content range is bonded to the carbon nanotubes. It is desirable to.

On the other hand, the manufacturing method of the present invention may be performed after the step of forming the carbon nanotubes, preparing a polyacrylonitrile-based carbon fiber precursor composition comprising the carbon nanotubes.

In the present invention, the step is carried out by a) a method of polymerizing a composition comprising a carbon nanotube, an acrylonitrile-based monomer, a polymerization initiator, and an organic solvent to which the functional group is bonded, or b) the functional group is bonded. The prepared carbon nanotubes may be mixed with a polyacrylonitrile-based polymer and an organic solvent.

Among them, since the first method (the method a) is a method of mixing the carbon nanotubes and the monomer and polymerizing them together, the first method (the method a) is included in the precursor composition as compared to the method of mixing the polymerized polymer and the carbon nanotubes (the method b). The content of the carbon nanotubes can be increased, and the prepared precursor composition can be used directly in the spinning process, which is the next step, so that the process can be simplified.

In this case, the method a) includes 0.1 to 30 parts by weight of carbon nanotubes to which the functional group is bonded, 0.01 to 0.5 parts by weight of a polymerization initiator, and 400 to 600 parts by weight of an organic solvent, based on 100 parts by weight of the acrylonitrile monomer. It can be carried out by a method of polymerizing the composition. In addition, as an auxiliary component, 1 to 1 or more components selected from the group consisting of methyl acrylate, methyl methacrylate, acrylic acid, methacrylic acid, and itaconic acid based on 100 parts by weight of the acrylonitrile monomer 15 parts by weight can be carried out by a method of polymerizing the composition further comprising.

In addition, the method b) may be performed by mixing 0.1 to 30 parts by weight of carbon nanotubes and 400 to 600 parts by weight of an organic solvent to which the functional group is bonded, based on 100 parts by weight of the polyacrylonitrile-based polymer.

Here, as the organic solvent, dimethyl sulfoxide, dimethylacetamide, dimethylformamide, or the like may be used.

On the other hand, the production method of the present invention may be performed after the step of producing the polyacrylonitrile-based carbon fiber precursor composition, to prepare a precursor fiber by spinning the composition.

In the above step, the spinning apparatus and the spinning conditions are not particularly limited, since the spinning apparatus can be carried out under ordinary spinning conditions using a spinning apparatus conventional in the art.

However, preferably, the polyacrylonitrile-based carbon fiber precursor composition prepared in the above step is extruded and spun through a spinning nozzle, and washed and desolvented while passing it through a coagulation bath filled with a coagulation solvent at 10 to 50 ° C. Precursor fibers can be prepared by stretching four to five times at the same time and winding them up.

On the other hand, the production method of the present invention, after the step of producing the precursor fiber, may perform the step of heat treatment and oxidation treatment of the precursor fiber.

The step is a step of thermally treating the precursor fiber to induce a cyclization reaction as shown in Scheme 1, and finally to prepare a carbon fiber by oxidation treatment.

[Reaction Scheme 1]

In this case, the heat treatment for the precursor fiber may be performed for 30 to 120 minutes at 200 to 300 ℃, the oxidation treatment may be carried out at 1000 to 1800 ℃.

Typically, in the case of polyacrylonitrile homo polymers, a high temperature is required in the cyclization reaction as in Scheme 1, but increasing the temperature may increase side reactions and decrease the mechanical properties of the fiber. Accordingly, a method of lowering the initiation temperature of the cyclization reaction by polymerizing a comonomer such as itaconic acid, which can act as a catalyst in the cyclization reaction, with an acrylonitrile monomer is mainly used. .

In view of the above, the present invention introduces a variety of functional groups capable of performing the same role as the comonomer to the surface of the carbon nanotubes, thereby allowing the use of a homopolymer without a comonomer and reducing the calorific value in the stabilization step. There is an advantage to produce a higher performance carbon fiber.

As such, the method for producing a polyacrylonitrile-based carbon fiber according to the present invention may include the above-described steps. However, in addition to the above-described steps, it may further include a step that can be conventionally performed in the art before or after each step, the above step is not limited to the manufacturing method of the present invention. .

Meanwhile, the present invention provides a polyacrylonitrile-based carbon fiber produced by the above-described method according to another embodiment.

Polyacrylonitrile-based carbon fiber according to the present invention has the advantage of excellent mechanical properties as manufactured by the above-described method. Specifically, according to the method for producing a polyacrylonitrile-based carbon fiber according to the present invention, the strength (strength) 0.5 GPa or more (preferably 0.5 to 0.5) compared to the polyacrylonitrile-based carbon fiber containing no carbon nanotubes 2.0 GPa, more preferably 0.9 to 1.4 GPa, and modulus of 50 GPa or more (preferably 50 to 200 GPa, more preferably 50 to 150 GPa), thereby improving mechanical properties. However, since the mechanical properties of the polyacrylonitrile-based carbon fiber may vary depending on the type and content of the carbon nanotubes used, the type, content and molecular weight of the acrylonitrile-based resin, the present invention is limited to the above numerical range. The person skilled in the art to which the present invention pertains will be able to control the physical properties of the polyacrylonitrile-based carbon fiber using various methods.

Such carbon fiber of the present invention is expected to be useful in various fields, such as composite material field, wind power generator material field, electrically conductive material field, aerospace field for automobile lightweight.

Best Mode for Carrying Out the Invention Hereinafter, preferred embodiments are described to facilitate understanding of the present invention. However, the following examples are intended to illustrate the present invention without limiting it thereto.

[ Example  And Comparative example ]

Example  One

(Formation step of the functional carbon nanotubes bonded)

0.1 g of carbon nanotubes (average diameter 10 nm, average length 1 μm, manufactured by Nanocyl) were placed in a round-bottomed flask, a nitrogen atmosphere was added, and 1 ml of purified dimethylformamide (DMF) was added and Sonication for 10 minutes.

Subsequently, 20 ml of thionyl chloride was slowly added dropwise to the flask, followed by reaction at 60 ° C. for 14 hours, and dried in a freeze dryer for 14 hours to remove the remaining thionyl chloride. Thereafter, 3 ml of DMF and 0.5 g of 5-amino isophthalic acid were added thereto, and the mixture was filtered after reacting at 57 ° C. for 14 hours. Thereafter, the resultant was washed with methanol to remove the remaining 5-amino isophthalic acid, and the remaining solids were collected and dried to form carbon nanotubes having functional groups (0.084 g, yield = 84%).

(Step of Producing Precursor Composition)

To 100 parts by weight of polyacrylonitrile polymer (manufacturer: Jilin Carbon Co., Ltd.), by mixing 1 part by weight of carbon nanotubes with the functional group, and 550 parts by weight of dimethyl sulfoxide (DMSO) by mixing the carbon fiber precursor composition Was prepared.

(Step of Producing Precursor Fiber)

The carbon fiber precursor composition was spun using a spinning equipment, which was stretched and wound five times while washing and desolventing while passing through a coagulation bath filled with a coagulation solvent (DMSO: water = 50: 50) at 15 ° C. Fiber precursor fibers were prepared.

(Heat treatment and oxidation treatment step for precursor fiber)

The carbon fiber precursor fiber was heat treated at 200 to 300 ° C. for 60 minutes in a flame resistant furnace, and oxidized at 1500 ° C. to produce carbon fiber.

Example  2

(Formation step of the functional carbon nanotubes bonded)

0.5 parts by weight of carbon nanotubes (average diameter 10 nm, average length 1 μm, manufacturer: Nanocyl) were mixed with sulfuric acid, and then sonicated for 30 minutes. Subsequently, 3 parts by weight of 5-amino isophthalic acid was added to the solution, 1.17 parts by weight of sodium nitrite was added, followed by cooling at 60 ° C. for 1 hour. The solution was then diluted with dimethylformamide (DMF), filtered, washed with ethanol until the filtrate became clear and dried.

(Step of Producing Precursor Composition)

To 100 parts by weight of polyacrylonitrile polymer (manufacturer: Jilin Carbon Co., Ltd.), 0.5 parts by weight of carbon nanotubes to which the functional groups are bonded, and 550 parts by weight of dimethyl sulfoxide (DMSO) were mixed to form a carbon fiber precursor composition. Was prepared.

(Step of Producing Precursor Fiber)

A precursor fiber was prepared in the same manner as in Example 1.

(Heat treatment and oxidation treatment step for precursor fiber)

Carbon fiber was prepared in the same manner as in Example 1.

Example  3

In the preparation step of the precursor composition of Example 2, carbon fibers were manufactured in the same manner as in Example 2, except that the carbon nanotubes to which the functional groups were bonded were mixed at 1 part by weight based on 100 parts by weight of the polyacrylonitrile polymer. .

Example  4

In the preparation step of the precursor composition of Example 2, carbon fibers were manufactured in the same manner as in Example 2, except that the carbon nanotubes to which the functional groups were bonded were mixed at 5 parts by weight based on 100 parts by weight of the polyacrylonitrile polymer. .

Example  5

(Formation step of the functional carbon nanotubes bonded)

It carried out in the same manner as in Example 2.

(Step of Producing Precursor Composition)

10 parts by weight of carbon nanotubes to which the functional group is bonded, 0.3 parts by weight of azobisisobutyronitrile (AIBN) as a polymerization initiator, and dimethyl sulfoxide (DMSO) 500 as an organic solvent, based on 100 parts by weight of acrylonitrile monomer. The parts by weight were mixed and polymerized at 60 ° C. with stirring at 200 rpm for 10 hours under a nitrogen atmosphere to prepare a precursor composition.

(Step of Producing Precursor Fiber)

A precursor fiber was prepared in the same manner as in Example 2.

(Heat treatment and oxidation treatment step for precursor fiber)

Carbon fibers were prepared in the same manner as in Example 2.

Comparative example  One

In the manufacturing step of the precursor composition of Example 2, carbon fibers were prepared in the same manner as in Example 2, except that a precursor composition including a polyacrylonitrile polymer was prepared without adding carbon nanotubes.

Comparative example  2

0.5 weight of the raw material carbon nanotubes of the functional group is not bonded to 100 parts by weight of the polyacrylonitrile polymer in the step of preparing the precursor composition without performing the step of forming the carbon nanotubes bonded to the functional group of Example 2 A carbon fiber was prepared in the same manner as in Example 2, except that the mixture was mixed in portions.

[ Test Example ]

A functional group Combined  Measurement of Properties of Carbon Nanotubes

For carbon nanotubes before and after the functional group according to Example 1, Raman Spectroscopy (Horiba Ltd), XPS (X-ray Photoelectron Spectroscopy, Model Name: AXIS-NOVA, Kratos Inc), and TGA (Thermogravimetry) Analysis, model name: Q50, manufacturer: TA instrument) was performed, the results are shown in Figs.

As a result, as the carbon nanotubes according to Example 1 bind the functional groups, as shown in FIG. 1, the D band was larger than that of the raw carbon nanotubes; Oxygen peaks appeared as shown in FIG. 2; In addition, as shown in Figure 3 it was confirmed that the weight loss appeared about 10%.

Carbon fiber  Mechanical property measurement

Strength and modulus were measured for the carbon fibers prepared in Examples 1 to 5 and Comparative Examples 1 and 2, respectively. In this case, the physical properties were measured using an Instron Universal Tester 5567 equipment, the results are shown in Table 1 below.

division Strength (GPa) Modulus of elasticity (GPa) Example 1 3.5 280 Example 2 3.2 250 Example 3 3.7 300 Example 4 3.5 320 Example 5 3.3 340 Comparative Example 1 2.3 190 Comparative Example 2 2.0 210

As shown in Table 1, the carbon fiber according to Examples 1 to 5 is manufactured using the carbon nanotubes bonded to the functional group according to the present invention, Comparative Example 1 and the functional group is not included in the carbon nanotubes Compared with Comparative Example 2 using the non-carbon nanotubes, it can be seen that the strength and elastic modulus are high, and thus the mechanical properties are excellent.

Claims (10)

Forming a carbon nanotube to which a functional group of Formula 1 is bonded;
Preparing a polyacrylonitrile-based carbon fiber precursor composition comprising the carbon nanotubes;
Spinning the composition to produce precursor fibers; And
Heat treating and oxidizing the precursor fibers
Method for producing a polyacrylonitrile-based carbon fiber comprising:
[Formula 1]

In Chemical Formula 1,
One to three of R ₁ to R ₅ are a carboxylic acid group (-COOH), a sulfonic acid group (-SO ₃ H), or a nitrile group (-CN), and the rest are hydrogen groups (-H);
R ₆ is a chemical bond, an ester bond (-COO-), or an amide bond (-CONH-);
However, when R ₆ is an ester bond (-COO-) or an amide bond (-CONH-), one to three of R ₁ to R ₅ are carboxylic acid groups (-COOH), and the rest are hydrogen groups (-H )to be. The method of claim 1,
The carbon nanotubes to which the functional groups are bonded have a content of the functional group of 1 to 40 parts by weight based on 100 parts by weight of carbon nanotubes. The method of claim 1,
The carbon nanotubes are single-walled nanotubes (SWNT), multi-walled nanotubes (MWNT), or a mixture thereof. The method of claim 1,
The carbon nanotube is a method of producing a polyacrylonitrile-based carbon fiber having an average diameter of 1 to 100 nm and an average length of 0.1 to 50 ㎛. The method of claim 1,
The polyacrylonitrile-based carbon fiber precursor composition is 0.1 to 30 parts by weight of carbon nanotubes, 0.01 to 0.5 parts by weight of a polymerization initiator, and 400 to 600 parts by weight of an organic solvent, based on 100 parts by weight of an acrylonitrile monomer. The manufacturing method of the polyacrylonitrile-type carbon fiber which superposed | polymerized the composition containing a part. The method of claim 5, wherein
The polyacrylonitrile-based carbon fiber precursor composition is one or more components selected from the group consisting of methyl acrylate, methyl methacrylate, acrylic acid, methacrylic acid, and itaconic acid based on 100 parts by weight of the acrylonitrile monomer Method of producing a polyacrylonitrile-based carbon fiber which is polymerized a composition further comprising 1 to 15 parts by weight. The method of claim 1,
The carbon fiber precursor composition is a method for producing a polyacrylonitrile-based carbon fiber comprising 0.1 to 30 parts by weight of carbon nanotubes and 400 to 600 parts by weight of an organic solvent in which the functional group is bonded to 100 parts by weight of polyacrylonitrile polymer. The method of claim 1,
The step of heat treating and oxidizing the precursor fiber is a polyacrylonitrile-based carbon fiber which is performed by heat treating the precursor fiber at 200 to 300 ℃ for 30 to 120 minutes and oxidizing it at 1000 to 1800 ℃. Manufacturing method. The method of claim 1,
Method for producing a polyacrylonitrile-based carbon fiber increased by 0.5 to 2.0 GPa and modulus of 50 to 200 GPa compared to polyacrylonitrile-based carbon fiber containing no carbon nanotubes. A polyacrylonitrile-based carbon fiber produced by the method according to any one of claims 1 to 9.

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