KR101881197B1 - Apparatus for preparing carbon nanotube fiber - Google Patents

Abstract

The present invention relates to an apparatus for producing carbon nanotube fibers.

Description

TECHNICAL FIELD [0001] The present invention relates to a carbon nanotube fiber manufacturing apparatus,

The present invention relates to an apparatus for producing carbon nanotube fibers.

Carbon nanotubes (CNTs), a kind of carbon isotopes, have a diameter of several to several tens of nanometers and are several hundreds of micrometers to several millimeters long, reported in the journal Nature in 1991 by Dr. Iijima, Due to its physical properties and high aspect ratio, research has been conducted in various fields. The inherent properties of these carbon nanotubes are due to the sp2 bond of carbon, stronger than iron, lighter than aluminum, and exhibit electrical conductivity similar to that of metals. According to the number of nanotubes, single-wall carbon nanotubes (SWNTs), double-wall carbon nanotubes (DWNTs), multi-walled carbon nanotubes (Multi- Wall carbon nanotube (MWNT), and can be divided into zigzag, armchair, and chiral structures depending on the asymmetry / chirality.

 Methods for fabricating carbon nanotube (CNT) fibers include forest radiation and direct radiation. The forest radiation is obtained by depositing a catalyst on a substrate, synthesizing a CNT fork in a direction perpendicular to the substrate, and pulling the CNT at the end of the substrate with a tweezers or a tape to form CNTs connected by van der Waals attraction between the CNTs It is a method to radiate CNT fiber while coming out. This method has the disadvantage that it can not increase the production amount because the continuous process is impossible.

On the other hand, carbon nanotube (CNT) fibers contain various kinds of impurities. Among them, the most abundant impurities are amorphous carbon which is decomposed in the gas phase and formed inside and outside of the fiber. These impurities must be removed because they degrade the quality of the fibers.

In general, amorphous carbon can be oxidized and removed at a temperature of 400-500 ° C. Accordingly, there is a method for removing amorphous carbon by passing the fibers through a heat source such as a furnace by a method of removing amorphous carbon. However, this method has a problem in that it is not economical because expensive furnaces must be used. And because of the length limitation of the furnace, there is a problem that it is uneconomical to install several furnaces in order to increase the retention time of the fibers. In another method, there is a method of lowering the moving speed of the fiber passing through the reactor, which also has a problem of lowering the productivity. Therefore, a new method for removing impurities is required.

Korean Patent No. 10-1286751

There is a problem that the apparatus for removing impurities from the carbon nanotube (CNT) fiber of the prior art is not economical. There is also a problem of lowering the productivity.

Accordingly, it is an object of the present invention to provide an apparatus for manufacturing carbon nanotube fibers which is capable of easily removing impurities and simplifying the apparatus.

In order to accomplish the above object, the present invention provides a cylindrical high temperature reactor main body having a reaction zone; An inlet for injecting a spinning material and carrier gas into the reaction zone of the body; Heating means for heating the reaction region; A discharge port installed at a lower end of the main body to discharge the carbon nanotube fibers; Winding means for collecting the discharged carbon nanotube fibers; A guide provided between the outlet and the winding means; And a voltage generator for applying a voltage to the guide, wherein the voltage is applied to the carbon nanotube fibers to remove impurities contained in the carbon nanotube fibers.

According to a preferred embodiment of the present invention, the inlet may include a spray nozzle for injecting the spinning material and a dispersing plate for injecting the carrier gas. In addition, the spinning material may be a catalyst precursor dispersed in a liquid or gaseous carbon compound, and the spinning material may further include a catalytic activator. According to a preferred embodiment of the present invention, the carrier gas may be a hydrocarbon gas, an inert gas, a reducing gas or a mixture thereof.

The present invention can provide a carbon nanotube fiber manufacturing apparatus capable of simply removing amorphous carbon by applying joule heating to carbon nanotube fibers. Further, the apparatus for producing carbon nanotube fibers of the present invention is simplified, and the economical efficiency is also excellent.

By using the apparatus for producing carbon nanotube fibers according to the present invention, it is possible to obtain carbon nanotube fibers which are free from impurities and excellent in strength and elasticity. Accordingly, it is desired to provide a reinforcing material for a multifunctional composite material, a strain and damage sensor using a stable and repeated piezoresistance effect, a transmission line using high conductivity, a high specific surface area, an electrochemical device using excellent mechanical characteristics and electrical conductivity, It is expected to be applicable to various fields such as microelectrode material, supercapacitor, actuator and the like.

Fig. 1 is a schematic view of a winding means provided with a conventional impurity removing device.
2 shows an apparatus for producing carbon nanotube fibers according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail. The following detailed description is merely an example of the present invention, and therefore, the present invention is not limited thereto.

In the drawings, like reference numerals are used for similar elements.

The term "and / or" includes any one or a combination of the plurality of listed items.

 It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it is to be understood that other elements may be directly connected or connected, or intervening elements may be present.

 The singular expressions include plural expressions unless otherwise specified.

 The terms "comprises", "having", or "having" mean that there is a feature, a value, a step, an operation, an element, a component or a combination thereof described in the specification, Does not exclude the possibility that a number, a step, an operation, an element, a component, or a combination thereof may be present or added.

 The term "carbon nanotube fibers" in the present specification refers to both carbon nanotubes grown in a fiber form or formed by fusing a plurality of carbon nanotubes in a fiber form.

Techniques for producing carbon nanotube fibers include solution spinning, array spinning, aerogel spinning and / or film twisting or rolling. The present invention follows a process of directly spinning carbon nanotube fibers or ribbons from a carbon nanotube aerogel formed immediately after the introduction of a spinning material in a reactor by using chemical vapor deposition (CVD).

In the direct spinning, carbon nanotubes are synthesized in a heating furnace by injecting carbon nanotubes at a constant rate in a vertical furnace together with a carrier gas by adding a catalyst to the carbon nanotubes, and pure carbon nanotubes Carbon nanotube fibers are continuously produced.

The catalyst precursor of the present invention is a substance which is not contained in the catalyst cycle but is changed into an active catalyst (or produces an active catalyst) in the course of the catalytic reaction, and in the present invention, the catalyst precursor forms a catalyst Then, CNT is synthesized.

FIG. 1 is a view of a winding means having a conventional impurity removing apparatus. In the conventional carbon nanotube (CNT) fiber manufacturing apparatus, a method of passing impurities through a heat source such as a furnace have. However, this method has a problem in that it is not economical because an expensive furnace must be used.

Accordingly, the inventors of the present invention solved this problem by manufacturing an apparatus for manufacturing carbon nanotube fibers using joule heating.

That is, a cylindrical high-temperature reactor body having a reaction region; An inlet for injecting a spinning material and carrier gas into the reaction zone of the body; Heating means for heating the reaction region; A discharge port installed at a lower end of the main body to discharge the carbon nanotube fibers; Winding means for collecting the discharged carbon nanotube fibers; A guide provided between the outlet and the winding means; And a voltage generator for applying a voltage to the guide, wherein the voltage is applied to the carbon nanotube fibers to remove impurities contained in the carbon nanotube fibers. The impurity may be amorphous carbon.

Hereinafter, the present invention will be described more specifically with reference to the drawings.

FIG. 2 illustrates an apparatus for manufacturing carbon nanotube fibers according to an embodiment of the present invention. Referring to FIG. A cylindrical high-temperature reactor main body 11 having a reaction zone; An inlet (10) for injecting a spinning material and a carrier gas into the reaction zone of the body; Heating means (13) for heating the reaction zone; A discharge port 14 for discharging the carbon nanotube fibers installed at the lower end of the main body; A winding means (16) connected to said outlet; Guides (15a, 15b, 15c) provided between the outlet and the winding means; And a voltage generator (17) for applying a voltage to a part of the guide.

The apparatus for producing carbon nanotube fibers according to the present invention may further comprise a spinning material supply unit for supplying a spinning material to the reactor body 11 at the inlet 10 and a carrier gas supply unit for supplying the carrier gas. In addition, the spinning material supply unit may include a mixer for dispersing the catalyst precursor in the gaseous or liquid carbon compound, and a transport pump for supplying the spinning material formed in the mixer to the spinneret spraying nozzle. The carrier gas may be introduced into the reactor body 11 through the inlet 10 from a carrier gas supply unit having a gas tank and flow control means. The inlet 10 may include a spray nozzle for injecting a spinning material and a dispersing plate for injecting a carrier gas. The inlet may be an injection nozzle, but is not limited thereto.

In the present invention, the heating means may be a heating furnace surrounding the reactor body, and the reaction region 12 may be heated to 1,000 to 3,000 캜. The high temperature region of the reactor may preferably maintain a temperature of 1,000 to 2,000 DEG C, 1,000 to 1,500 DEG C or 1,000 to 1,300 DEG C, and more preferably 1,100 to 1,200 DEG C. [ The temperature in the high temperature region of the reactor influences the rate at which carbon is diffused into the catalyst to control the growth rate of the carbon nanotube. When synthesizing carbon nanotubes by chemical vapor deposition, generally, the higher the synthesis temperature, the higher the crystallinity and strength as the growth rate of carbon nanotubes increases.

According to a preferred embodiment of the present invention, the discharge port 14 may be connected to a winding means 16 for winding up and collecting carbon nanotube fibers containing impurities discharged from the lower end of the cylindrical high temperature reactor main body . According to a preferred embodiment of the present invention, the winding means 16 may comprise at least one selected from a spindle, a reel, a bobbin, a drum and a conveyor, and preferably a bobbin have. However, the present invention is not limited to this, and any means capable of stably winding the discharged carbon nanotube fibers can be used. The winding speed affects the orientation of the carbon nanotubes in the fiber in the direction of the fiber axis, thus determining the thermal, electrical and / or physical properties of the carbon nanotube fibers. Preferably, it can be wound in the range of 5 to 100 rpm.

The winding means may be one or more, and preferably one. And the guide may be provided between the outlet and the winding means. According to a preferred embodiment of the present invention, the guide may include at least one selected from a copper electrode, a tungsten electrode, a stainless electrode, a gold electrode, and a silver electrode, and may be a copper electrode. The guide may be two or more, preferably two, more preferably three. Further, according to a preferred embodiment of the present invention, a gas separation device may further be provided between the outlet and the winding means. The gas separation device separates the gas remaining in the carbon nanotube fibers. The gas separation apparatus may include at least one selected from a water tank and a glove box. According to a preferred embodiment of the present invention, at least two of the guides may be connected to a voltage generator. If the number of the guides is three or more, at least one of the guides may be included in the gas separation device.

For example, as shown in Fig. 2, one guide 15a is provided in the water tank, and two guides 15b and 15c and one winding means 16 are sequentially provided out of the water tank. Specifically, the carbon nanotube fibers discharged to the discharge port pass through the guide in the water tank and move to the guide outside the water tank. At this time, the carbon nanotube fibers as the continuous aggregate of the cylindrical carbon nanotubes can be contracted as they pass through the water tank, so that they can be changed into a more threadlike shape. Then, the carbon nanotube fibers 19 containing the impurities passing through the water tank move to the guides 15b and 15c connected to the voltage generator, and the voltage is applied. That is, in the present invention, the carbon nanotube fibers 19 containing the impurities discharged from the discharge port slidably move in the guide, and become the carbon nanotube fibers 20 that have been heated in a line. The impurities include amorphous carbon, and the carbon nanotube fibers containing the impurities generate Joul heating in the fibers themselves, and the amorphous carbon is removed. Thus, the carbon nanotube fibers 21 from which the impurities are finally removed are wound. Meanwhile, the amorphous carbon can be oxidized and removed at a temperature of 300 to 600 ° C. Thus, the voltage may be between 1 and 20 volts, and preferably between 9 and 11 volts. If it is less than 1V, there may be a problem that the amorphous carbon on the surface of the carbon nanotube fiber is not removed, and if it is more than 20V, the carbon nanotube, which is a crystalline carbon, may be oxidized and removed.

Specifically, the reaction in the carbon nanotube fiber production apparatus of the present invention will be described. The radiation material and the carrier gas are introduced into the reactor through the inlet. When the catalyst precursor contained in the spinning material is supplied to the reactor, a catalyst is formed. The formed catalyst is synthesized in the reaction zone 12 while flowing from the upper end to the lower end of the reactor. Then, the synthesized carbon nanotubes are successively gathered by growing or fusing, and cylindrical carbon nanotube fibers are formed. At this time, the CNT-grown catalyst particles move to the lower end, and the formed CNT fibers are discharged through the discharge port 14 at the lower end of the reactor body and the heating furnace. Then, the carbon nanotube fibers are collected by the winding means 16 and taken out from the high temperature region. And slidably moves on the guide provided in the winding means. At the same time, a voltage is applied to the guide by a voltage generator to remove impurities contained in the carbon nanotube fibers. In addition, unreacted gases, including carrier gas and / or unreacted radiation, are vented through the exhaust port 18. The catalyst is discharged together with the CNT because the CNT grows, and a small amount of unreacted catalyst is also buried in the CNT and discharged. The unreacted gas exhaust port remaining in the reaction region may be provided between the heating means and the discharge port or at the rear end of the CNT fiber discharge port. And the unreacted gas may comprise unreacted radiation and carrier gas.

On the other hand, the spinning material may include a carbon compound in a gas form as well as a liquid form. The liquid or gaseous carbon compound diffuses as a carbon source as a catalyst and is synthesized into carbon nanotubes. The molecular weight distribution, concentration, viscosity, surface tension, dielectric constant and properties of the solvent used are taken into consideration.

According to a preferred embodiment of the present invention, the liquid or gaseous carbon compound is selected from the group consisting of methane, ethylene, acetylene, methyl acetylene, vinyl acetylene, ethanol, methanol, propanol, acetone, xylene, chloroform, ethyl acetic acid, And one or more selected from the group consisting of polyethylene glycol, ethyl formate, mesitylene, tetrahydrofuran (THF), dimethylformamide (DMF), dichloromethane, hexane, benzene, carbon tetrachloride and pentane. Specifically, the liquid carbon compound may be at least one selected from the group consisting of ethanol, methanol, propanol, acetone, xylene, chloroform, ethyl acetate, diethyl ether, polyethylene glycol, ethyl formate, mesitylene, tetrahydrofuran And may include one or more selected from the group consisting of formamide (DMF), dichloromethane, hexane, benzene, carbon tetrachloride, and pentane. (C ₂ H ₅ OH), xylene (C ₈ H ₁₀ ), diethyl ether [(C ₂ H ₅ ) _{2 O} ], polyethylene glycol [(CH ₂ -CH ₂ -O) ₉ ] 1-propanol _{(CH 3 CH 2 CH 2 OH} ), acetone (CH ₃ OCH _3), ethyl formate (CH ₃ CH ₂ COOH), benzene (C ₆ H _6), hexane (C ₆ H ₁₄₎ and mesitylene [C ₆ H ₃ (CH ₃ ) ₃ ]. The gas-phase carbon compound may include at least one selected from the group consisting of methane, ethylene, acetylene, methyl acetylene, and vinyl acetylene.

According to a preferred embodiment of the present invention, the spinning material may be a catalyst precursor dispersed in a liquid or gaseous carbon compound. The spinning material may be mixed with 0.5 to 5 wt%, preferably 1 to 5 wt%, or 1.5 to 4 wt% of the catalyst precursor to the liquid or gaseous carbon compound. If excess catalyst precursor is used in comparison with the liquid or gaseous carbon compound of the spinning material, the catalyst acts as an impurity and it is difficult to obtain high purity carbon nanotube fibers. It may also be a factor that hinders the thermal, electrical and / or physical properties of the carbon nanotube fibers. In the present invention, the catalyst precursor may include at least one selected from the group consisting of metallocene including ferrocene, iron, nickel, cobalt, platinum, ruthenium, molybdenum, vanadium and oxides thereof, no. The catalyst precursor may also be in the form of nanoparticles. And preferably in a metallocene form such as ferrocene, which is a compound containing iron, nickel, cobalt and the like; Iron such as iron chloride (FeCl ₂ ); cobalt; And a nickel atom may be used as the catalyst precursor.

According to a preferred embodiment of the present invention, the spinning material may further include a catalytic activator. Generally, carbon nanotubes are synthesized by diffusion of carbon into the catalyst in the molten state of the catalyst, followed by precipitation of the carbon nanotubes. The catalyst activator is used as a promoter in the synthesis of carbon nanotubes to increase the carbon diffusion rate, Thereby synthesizing carbon nanotubes. As the catalytic activator, thiophene (C ₄ H ₄ S) may be used. Thiophene reduces the melting point of the catalyst and removes the amorphous carbon, allowing synthesis of high purity carbon nanotubes at low temperatures. The content of the catalytic activator may also affect the structure of the carbon nanotubes. For example, when 1 to 5% by weight of thiophene is mixed with ethanol as the carbon compound, multiwall carbon nanotube fibers are obtained And when the thiophene is mixed with ethanol in an amount of 0.5% by weight or less, single-walled carbon nanotube fibers can be obtained. According to a preferred embodiment of the present invention, the catalyst precursor and the catalytic activator may be liquid in the liquid carbon compound, and may be vapor in the vapor carbon compound. Therefore, the liquid carbon compound can be injected by dissolving the catalyst precursor or the catalytic activator, and vaporized into the gas-phase carbon compound to be injected into the gas form.

According to a preferred embodiment of the present invention, the carrier gas may be a hydrocarbon gas, an inert gas, a reducing gas or a mixture thereof. The inert gas may be argon, nitrogen, or a mixed gas thereof, and the reducing gas may be hydrogen, ammonia, or a mixed gas thereof.

Another aspect of the present invention provides a method for producing carbon nanotube fibers using the carbon nanotube fiber manufacturing apparatus of the present invention. (A) forming a carbon nanotube fiber as a continuous aggregate of carbon nanotubes by reacting a spinning material with a carrier gas; And (b) winding the carbon nanotube fibers, wherein a voltage is applied to the carbon nanotube fibers during the steps (a), (b), (b), or And removing impurities contained in the carbon nanotube fibers. Preferably, the carbon nanotube fibers formed in the step (a) may be applied with a voltage after passing through the water tank. And may be wound in the step (b). The carbon nanotube fibers can be shrunk as they pass through the water tank, and can be changed into a more threadlike shape. And the configuration may be the same as described above.

10: inlet 11: reactor body 12: reaction zone
13: Heating means 14: Outlets 15a, 15b, 15c: Guide
16: winding means 17: voltage generator 18: exhaust port
19: Carbon nanotube fibers containing impurities
20: joule heated carbon nanotube fibers
21: Carbon nanotube fibers with impurities removed

Claims (19)

A cylindrical high-temperature reactor body having a reaction zone;
An inlet for injecting a spinning material and carrier gas into the reaction zone of the body;
Heating means for heating the reaction region;
A discharge port installed at a lower end of the main body to discharge the carbon nanotube fibers;
Winding means for collecting the discharged carbon nanotube fibers;
A guide provided between the outlet and the winding means; And
And a voltage generator for applying a voltage to the guide,
And a voltage is applied to the carbon nanotube fibers to remove impurities contained in the carbon nanotube fibers. The method according to claim 1,
Wherein the guide includes at least one selected from a copper electrode, a tungsten electrode, a stainless electrode, a gold electrode, and a silver electrode. The method according to claim 1,
Further comprising a gas separation device between the outlet and the winding means. The method of claim 3,
Wherein the gas separation device comprises at least one selected from a water tank and a glove box. The method according to claim 1,
Wherein the guide is at least two. The method of claim 5,
Wherein at least two of the guides are connected to a voltage generator. The method according to claim 1,
Wherein at least one guide is included in the gas separation device when the number of the guides is three or more. The method according to claim 1,
Wherein the voltage of the voltage generator is 1 to 20V. The method according to claim 1,
Wherein the impurity comprises amorphous carbon. The method according to claim 1,
Wherein the inlet comprises a spinning material supply unit for supplying a spinning material, and a carrier gas supply unit for supplying a carrier gas. The method according to claim 1,
Wherein the winding means comprises at least one selected from a spindle, a reel, a bobbin, a drum, and a conveyor. The method according to claim 1,
Wherein the inlet comprises an injection nozzle for injecting a spinning material and a dispersing plate for injecting a carrier gas. The method according to claim 1,
Wherein the heating means is a heating furnace enclosing the reactor main body, and the reaction region is heated to 1,000 to 3,000 占 폚. The method according to claim 1,
Wherein the spinning material is a catalyst precursor dispersed in a liquid or gaseous carbon compound. 15. The method of claim 14,
The liquid or gaseous carbon compound may be at least one selected from the group consisting of methane, ethylene, acetylene, methyl acetylene, vinylacetylene, ethanol, methanol, propanol, acetone, xylene, chloroform, ethyl acetic acid, diethyl ether, polyethylene glycol, Wherein the carbon nanotube fiber comprises at least one selected from the group consisting of tetrahydrofuran (THF), dimethylformamide (DMF), dichloromethane, hexane, benzene, carbon tetrachloride and pentane. Claim 14
Wherein the catalyst precursor comprises at least one selected from the group consisting of metallocene including ferrocene, iron, nickel, cobalt, platinum, ruthenium, molybdenum, vanadium and oxides thereof. 15. The method of claim 14,
Wherein the spinning material further comprises a catalytic activator. The method of claim 14 or claim 17,
The catalyst precursor and the catalytic activator are liquid in the liquid carbon compound,
And the carbon compound is in a gaseous phase. The method according to claim 1,
Wherein the carrier gas is a hydrocarbon gas, an inert gas, a reducing gas, or a mixed gas thereof.

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