Carbon nanotube dispersion liquid production system and carbon nanotube dispersion liquid production method using the same

Abstract

To provide a carbon nanotube fluid dispersion production system and a fluid dispersion production method of the carbon nanotube using the same.SOLUTION: A carbon nanotube fluid dispersion production system in one embodiment comprises: a mixing unit to which a solvent and carbon nanotube are supplied, and which stores a mixture in which the solvent and the carbon nanotube are mixed; a first dispersion unit which is coupled to the mixing unit, primarily disperses the carbon nanotube by actuation of a rotor and a stator, and then secondarily disperses the carbon nanotube so that a flexure section is formed on the carbon nanotube while discharging the carbon nanotube through an open hole on the stator; and second dispersion means for, when the mixture which is secondarily dispersed from the mixing unit is circulated again to the mixing unit, selectively cutting the flexure section of the carbon nanotube by laser radiation for tertiarily dispersing the carbon nanotube.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a carbon nanotube dispersion production system and a carbon nanotube dispersion production method using the same, and more particularly to a carbon nanotube dispersion production system that can increase the dispersion rate without damaging carbon nanotubes with mechanical force, and a carbon nanotube dispersion production method using the same. [Background technology]

[0002] Generally, carbon nanotubes (CNTs) are substances in which one carbon atom is bonded to another carbon atom in a hexagonal honeycomb shape to form a tube. Their diameters range from 1nm to 100nm, their lengths reach several hundred micrometers, and their anisotropy is very large.

[0003] Such carbon nanotubes can be classified into single-walled carbon nanotubes, double-walled carbon nanotubes, multi-walled carbon nanotubes, rope carbon nanotubes, etc., and have high electrical conductivity comparable to that of metals due to the overlap of π electrons present in the outer wall.

[0004] Multifunctional nanocomposite materials can be developed by utilizing the excellent mechanical properties and electrical conductivity of the carbon nanotubes. For example, the nanocomposite material may be a composite material in which carbon nanotubes are added to a non-conductive material to impart conductivity, or a composite material in which carbon nanotubes are added as a reinforcing material for a polymer resin.

[0005] However, since the carbon nanotubes are obtained in an aggregated state due to van der Waals forces during the synthesis process, it is difficult to uniformly disperse the carbon nanotubes in a liquid or slurry. Carbon nanotubes that exist in an aggregated state as described above increase the viscosity of the liquid or slurry, making it difficult to handle, and it is difficult to ensure efficient electron conduction paths, resulting in low utilization of the dispersion in subsequent processes.

[0006] Therefore, the process of dispersing the carbon nanotubes into individual bodies is an important step in the development of composite materials with excellent physical properties.

[0007] Meanwhile, the carbon nanotubes can be manufactured by an arc discharge method, a laser evaporation method, a chemical vapor deposition method, and the like. Among the above-mentioned manufacturing methods, the representative chemical vapor deposition method produces carbon nanotubes by dispersing and reacting metal catalyst particles and a hydrocarbon-based raw material gas in a high-temperature fluidized bed reactor. That is, the metal catalyst is suspended in the fluidized bed reactor by the raw gas and reacts with the raw gas to grow carbon nanotubes.

[0008] During the synthesis of carbon nanotubes, an aggregation phenomenon occurs between individual carbon nanotube particles. Physical aggregation is when nanotube particles become entangled with each other at the micro level, while chemical aggregation is when nanotube particles aggregate due to surface attractive forces such as intermolecular van der Waals forces at the nanometer level.

[0009] Such a phenomenon of aggregation of carbon nanotubes prevents the formation of a three-dimensional network structure that can improve mechanical strength and conductive properties, and therefore, the dispersion technique of carbon nanotubes is very important. Therefore, in order to fully utilize the physical and chemical characteristics of the carbon nanotubes, it is urgently necessary to develop a method for minimizing the length of the carbon nanotubes and dispersing them without causing deterioration of their physical properties. The contents described in this Background Art are created to deepen understanding of the background of the invention, and may include contents that are not prior art already known to those having ordinary skill in the art to which this technology pertains. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Patent Publication No. 2017-043520 Summary of the Invention [Problem to be solved by the invention]

[0011] An embodiment of the present invention provides a carbon nanotube dispersion manufacturing system that can prevent damage to carbon nanotubes due to mechanical forces and increase the degree of dispersion when manufacturing a carbon nanotube dispersion to be used as a battery conductive material, and a carbon nanotube dispersion manufacturing method using the same. [Means for solving the problem]

[0012] In one or more embodiments of the present invention, a system for manufacturing a carbon nanotube dispersion liquid may be provided, including a mixer to which a solvent and carbon nanotubes are respectively supplied and in which a mixture of the solvent and the carbon nanotubes is stored; a first dispersing device connected to the mixer for primarily dispersing the carbon nanotubes by operating a rotor and a stator and then secondary dispersing the carbon nanotubes by releasing them through through holes on the stator to form bent sections in the carbon nanotubes; and a second dispersing device for selectively cutting the bent sections of the carbon nanotubes by irradiating a laser when the secondary dispersed mixture from the mixer is recirculated back to the mixer, thereby performing tertiary dispersion.

[0013] The mixing device may also include a solvent tank in which the solvent is stored, a carbon nanotube tank in which the carbon nanotubes are stored, and a mixing tank connected to the solvent tank and the carbon nanotube tank, respectively, and mixing the solvent and the carbon nanotubes supplied from the solvent tank and the carbon nanotube tank, respectively, via an internal agitator.

[0014] The carbon nanotube tank may also be configured such that the carbon nanotubes are fed in a set amount via an automatic feeder.

[0015] In addition, the first dispersion device is connected to the mixer and includes a storage tank to which the mixed liquid is supplied from the mixer, the rotor has a rotation axis installed in the same direction as the inflow direction of the mixed liquid and is disposed in the center of the storage tank so as to rotate in a direction perpendicular to the inflow direction of the mixed liquid, the stator has an open side on the inflow direction side of the mixed liquid and is fixed to the storage tank together with a drive motor of the rotor via the other closed side, and a plurality of through holes may be formed on a peripheral surface surrounding the rotor.

[0016] The diameter of the through hole of the stator may be set in the range of 20 mm to 200 mm.

[0017] The distance between the rotor and the stator can be set in the range of 10 mm to 500 mm.

[0018] The second dispersion device may include a laser beam device disposed toward a connecting pipe through which the mixed liquid moves from the first dispersion device to the mixer.

[0019] The connecting pipe may be made of optical glass.

[0020] The amount of energy of the laser irradiated by the laser beam device is 250 mJ / cm 2 More than 600mJ / cm 2 It can be set in the following range:

[0021] In one or more embodiments of the present invention, in a method for producing a carbon nanotube dispersion liquid using the carbon nanotube dispersion liquid producing system, a method for producing a carbon nanotube dispersion liquid may be provided, comprising: a first step of mixing a liquid solvent and a powdery carbon nanotube in a set amount through a mixer to form a mixture; a second step of moving the mixture to a first dispersing device and primarily dispersing the carbon nanotubes by the rotational force of a rotor of the first dispersing device; a third step of discharging the primarily dispersed carbon nanotubes to the outside of the stator through a through hole of the stator by the rotational force of the rotor to secondarily disperse the carbon nanotubes; and a fourth step of tertiarily dispersing the secondarily dispersed carbon nanotubes using a laser while passing through a second dispersing device.

[0022] The first step may include the steps of supplying a set amount of the solvent stored in a solvent tank to a mixing tank by operating a motor, supplying a set amount of the carbon nanotubes stored in a carbon nanotube tank to the mixing tank, and mixing the solvent and the carbon nanotubes by an agitator inside the mixing tank to form the mixed liquid.

[0023] The second step may include moving the mixed liquid from the mixer to a storage tank of the first dispersion device by the rotational force of a rotor of the first dispersion device, and debundling the carbon nanotubes between the rotor and the stator as the rotor rotates, thereby performing primary dispersion.

[0024] The third step may be a step of secondary dispersion in which the carbon nanotubes are discharged to the outside through a plurality of through holes on the stator by a rotational force of the rotor, thereby forming bent sections in the carbon nanotubes.

[0025] The fourth step may include irradiating the second-dispersed mixture with a laser when the mixture is circulated through the mixer, thereby cutting the bent portions of the carbon nanotubes and dispersing them thirdly.

[0026] In the fourth step, the amount of energy is 250 mJ / cm 2 More than 600mJ / cm 2 It may be characterized by utilizing the following ranges of lasers: Effect of the Invention

[0027] The carbon nanotube dispersion manufacturing system and carbon nanotube dispersion manufacturing method using the same according to an embodiment of the present invention have the effect of increasing the dispersibility of carbon nanotubes without damaging them with mechanical force when manufacturing a carbon nanotube dispersion to be used as a battery conductive material.

[0028] In other words, the carbon nanotube dispersion manufacturing system and the carbon nanotube dispersion manufacturing method using the same debundle and bend the carbon nanotubes using the shear force and centrifugal force between the rotor and stator to increase the deformation rate, and selectively cut only the sections with the high deformation rate by irradiating a laser, thereby minimizing physical damage to the carbon nanotubes and dispersing them.

[0029] Other advantages that are obtained or expected by the embodiments of the present invention are directly or implicitly disclosed in the detailed description of the embodiments of the present invention, i.e., various advantages that are expected by the embodiments of the present invention are disclosed in the detailed description below. [Brief description of the drawings]

[0030] [Figure 1] 1 is an overall configuration diagram of a carbon nanotube dispersion production system according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a configuration diagram of a first dispersion device applied to a carbon nanotube dispersion production system according to an embodiment of the present invention. [Diagram 3] 1 is a diagram showing a state of carbon nanotubes dispersed in a carbon nanotube dispersion production system and a carbon nanotube dispersion production method using the same according to an embodiment of the present invention; [Figure 4] 2 is a flow chart of a method for preparing a carbon nanotube dispersion according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings, in which: FIG. 1 is a block diagram of a semiconductor device according to an embodiment of the present invention;

[0032] In order to clearly describe the present invention, parts that are not directly related to the description will be omitted, and the same reference numerals will be used throughout the specification to refer to the same or similar components.

[0033] In addition, in the following description, the names of the components are divided into first, second, etc., in order to distinguish between the components that have the same names, and the order is not necessarily limited to that order.

[0034] The carbon nanotube dispersion manufacturing system and method using the same according to an embodiment of the present invention are applied to prepare a carbon nanotube dispersion used as a battery conductive material.

[0035] The term "dispersion" as used below is used in its general sense to refer to the phenomenon in which carbon nanotube aggregates are physically cut or chemically treated to reduce the volume and length of the aggregates, or the carbon nanotube aggregates are untangled and dispersed.

[0036] FIG. 1 is a diagram showing the overall configuration of a carbon nanotube dispersion production system according to an embodiment of the present invention. Referring to FIG. 1, the carbon nanotube dispersion preparation system includes a mixer 10, a first dispersing device 30, and a second dispersing device 40.

[0037] The mixing device 10 includes a solvent tank 11 in which a solvent in a liquid state is stored. Here, the solvent may be N-Methyl-2-pyrrolidone (NMP) or an aqueous solution.

[0038] The mixer 10 also includes a carbon nanotube tank 13 in which powdered carbon nanotubes (1, see FIG. 3) are stored.

[0039] Here, the carbon nanotubes 1 play an important role in improving the durability of the battery due to their high conductivity and mechanical rigidity. Therefore, it is advantageous that the carbon nanotubes 1 are not damaged during dispersion so that the conductivity is not reduced.

[0040] The solvent tank 11 and the carbon nanotube tank 13 are each connected to a mixing tank 15 . More specifically, the solvent tank 11 and the mixing tank 15 are connected to each other via a flow passage pipe 20a, and a motor M1 is provided in the flow passage pipe 20a. The solvent can be moved to the mixing tank 15 by driving the motor M1.

[0041] In addition, the carbon nanotube tank 13 is disposed above the mixing tank 15, and the carbon nanotube tank 13 can supply a set amount of carbon nanotubes 1 to the mixing tank 15 through an automatic feeder (Feeder 131). At this time, the automatic feeder 131 can be applied with a general technique for automatically feeding a set amount of objects.

[0042] When the solvent and the carbon nanotubes 1 are supplied to the mixing tank 15 in a set amount, they are mixed by a stirrer 151 arranged inside the mixing tank 15 . The agitator 151 rotates by the operation of a motor M2 and serves to mix the solvent and the carbon nanotubes 1 to prepare a mixture.

[0043] FIG. 2 is a schematic diagram of a first dispersion device applied to a carbon nanotube dispersion production system according to an embodiment of the present invention, and FIG. 3 is a diagram showing the state of carbon nanotubes dispersed in a carbon nanotube dispersion production system according to an embodiment of the present invention and a carbon nanotube dispersion production method using the same.

[0044] 2 and 3, the first dispersing device 30 includes a storage tank 31 connected to the mixing tank 15 via a fluid pipe 20b. At this time, it is preferable that the storage tank 31 is connected to the lower surface of the mixing tank 15 through a flow passage pipe 20b. A rotor (33) is installed in the center of the storage tank (31).

[0045] The rotation shaft 331 of the rotor 33 is arranged in the same direction as the inflow direction of the mixed liquid, and the rotor 33 is configured to rotate in a direction perpendicular to the inflow direction of the mixed liquid. The rotor 33 rotates with the rotary shaft 331 connected to a driving motor M3 arranged outside the storage tank 31.

[0046] The rotor 33 allows the mixed liquid in the mixing tank 15 to automatically flow into the storage tank 31 by rotating. In addition, a stator (35) surrounding the rotor 33 is installed inside the storage tank 31. The stator 35 has an open side on the inflow direction side inside the storage tank 31, and is fixed to the storage tank 31 together with the drive motor M3 of the rotor 33 via the other closed side. That is, the mixed liquid flows into the space between the rotor 33 and the stator 35 through the open side surface of the stator 35 .

[0047] As the rotor 33 rotates, a shear force P1 is generated between the rotor 33 and the stator 35, which causes the carbon nanotubes 1 to be primarily dispersed through debundling (see arrow A in FIG. 3). The debundling means that the aggregated carbon nanotubes 1 are separated into individual pieces.

[0048] At this time, the distance D1 between the rotor 33 and the stator 35 can be set in the range of 10 mm to 500 mm. This is a set value for dispersing the carbon nanotubes 1 by applying a shear force thereto, and for minimizing wear on the rotor 33 and the stator 35 . Further, a plurality of through holes 351 are formed in the peripheral surface of the stator 35 .

[0049] The mixture primarily dispersed between the rotor 33 and the stator 35 is forced to exit to the outside of the stator 35 via each through-hole 351 of the stator 35 by the centrifugal force P2 of the rotating rotor 33. The through hole 351 may be formed in a circular or rectangular shape.

[0050] At this time, the carbon nanotubes 1 are secondarily dispersed by bending, where a bent section 3 is formed, while passing through the through holes 351 (see arrow B in FIG. 3). The deformation rate (strain) of the bending section 3 is maximum. That is, the curved section 3 on the carbon nanotube 1 can be easily deformed even with a small force.

[0051] Regardless of whether the through hole 351 is circular or rectangular, the size D2 thereof may be set in the range of 20 mm to 200 mm. This is a set value taking into consideration the size of the carbon nanotube 1 .

[0052] Meanwhile, the mixture that has passed through the first dispersing device 30 is recirculated to the mixing tank 15 . At this time, a second dispersing device 40 is provided between the mixing tank 15 and the first dispersing device 30 .

[0053] The second dispersion device 40 includes a laser beam device 43 disposed toward a connecting pipe 41 through which the mixed liquid moves from the first dispersion device 30 to the mixing tank 15 . The connecting pipe 41 is formed in a certain area of ​​the flow passage pipe 20c through which the mixed liquid circulating to the mixing tank 15 via the storage tank 31 moves. The connecting pipe 41 may be integrally formed with the flow passage pipe 20c, or may be manufactured separately and then assembled with the flow passage pipe 20c.

[0054] For example, the connecting pipe 41 is made of optical glass. The connecting tube 41 made of optical glass can easily absorb the laser light L irradiated from the laser beam 43 . The bent section 3 of the carbon nanotube 1 is selectively cut by the second dispersion device 40 to perform tertiary dispersion (see arrow C in FIG. 3).

[0055] At this time, the energy of the laser irradiated by the laser beam device 43 is 250 mJ / cm 2 More than 600mJ / cm 2 It can be set in the following ranges: This is a value larger than the deformation rate of the bent section 3 of the carbon nanotube 1, and is a set value that prevents the remaining area excluding the bent section 3 from being deformed.

[0056] A method for preparing a carbon nanotube dispersion using the above-configured carbon nanotube dispersion preparation system is as follows. FIG. 4 is a flow chart of a method for preparing a carbon nanotube dispersion according to an embodiment of the present invention.

[0057] Referring to FIG. 4, a set amount of solvent is supplied from the solvent tank 11 to the mixing tank 15, and a set amount of carbon nanotubes 1 is supplied from the carbon nanotube tank 13 to the mixing tank 15 (S10).

[0058] In the mixing tank 15, the solvent and the carbon nanotubes 1 are mixed through an agitator 151 to prepare a mixture at a set ratio (S20).

[0059] While the mixture is mixed in the mixing tank 15, the mixture is dispersed while circulating through the first dispersing device 30 and the second dispersing device 40 and back to the mixer 10, which will be described later. However, the circulation process and the mixing process performed during the circulation can be continued for different periods depending on the concentration of carbon nanotubes in the mixture.

[0060] For example, the carbon nanotubes 1 and the solvent may be mixed to form a mixture of 0.1 wt % carbon nanotubes. At this time, the circulation process in which the carbon nanotubes 1 are dispersed in the mixture may be repeated for a minimum of 1 hour to a maximum of 5 hours.

[0061] Alternatively, the carbon nanotubes 1 and the solvent can be mixed to form a 3 wt % mixture, and in this case, the circulation process in which the carbon nanotubes 1 pass through the first dispersion device 30 and the second dispersion device 40 can be repeated for a minimum of 5 hours to a maximum of 24 hours.

[0062] Next, the mixture liquid automatically moves to the first dispersion device 30 side. That is, the mixed liquid mixed in the mixer 10 is sucked into the first dispersing device 30 by the rotational force of the rotor 33 of the first dispersing device 30 and moves. At this time, the rotor 33 rotates to debundle the carbon nanotubes 1 between the rotor 33 and the stator 35, thereby dispersing them primarily (S30, see arrow A in FIG. 3).

[0063] As described above, the primarily dispersed carbon nanotubes 1 pass through the through holes 351 of the stator 35 by the rotational force of the rotor 33 and are discharged to the outside of the stator 35 . At this time, the carbon nanotubes 1 are bent at a certain region while passing through the through holes 351, so that the bent section 3 is formed, thereby performing secondary dispersion (S40, see arrow B in FIG. 3).

[0064] The deformation ratio of the bending section 3 is maximum. That is, the force between carbon atoms is minimized in the bent section 3 of the carbon nanotube 1 .

[0065] Next, the secondly dispersed carbon nanotubes 1 are pushed and moved toward the second dispersion device 40 by the rotation of the rotor 33 . The carbon nanotube 1 is subjected to a third dispersion in which the bent section 3 is cut by the energy of a laser irradiated from a laser beam device 43 (S50, see arrow C in FIG. 3).

[0066] By using the laser beam device 43, only the bent section 3 on the carbon nanotube 1 is selectively cut. That is, the laser breaks the van der Waals forces between the carbon atoms in the carbon nanotubes 1 . The above-mentioned first dispersion, second dispersion, and third dispersion are continuously repeated for a required period of time.

[0067] Therefore, the carbon nanotube dispersion production system and the carbon nanotube dispersion production method using the same according to the embodiment of the present invention can disperse the carbon nanotubes 1 without damaging them with mechanical force.

[0068] In other words, the carbon nanotube dispersion manufacturing system and the carbon nanotube dispersion manufacturing method using the same debundle the carbon nanotube 1 using a shear force P1 between a rotor 33 and a stator 35, then bend it using a centrifugal force P2 to form a bent section 3, and irradiate a laser to apply energy corresponding to the carbon-carbon double bond energy (C=C) of the carbon nanotube 1 to selectively cut only the bent section 3, thereby minimizing physical damage to the carbon nanotube 1.

[0069] In addition, the carbon nanotube dispersion manufacturing system and the carbon nanotube dispersion manufacturing method using the same according to the embodiment of the present invention can simultaneously perform debundling, bending, and cutting processes in one device, thereby reducing process time and costs.

[0070] Although a preferred embodiment of the present invention has been described above with reference to the drawings, it will be understood that a person having ordinary skill in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the present invention as set forth in the following claims. [Explanation of symbols]

[0071] 1. Carbon Nanotubes 3. Bend Section 10 Mixing device 11 Solvent tank 13 Carbon Nanotube Tank 15 Mixing Tank 20a, 20b, 20c flow pipe 30 1st dispersion device 31 Storage Tank 33 Rotor 35 Stator 40 Second dispersion device 41 Connecting pipe 43 Laser Beam Device 131 Automatic Feeder 151 Stirrer 331 Rotational Axis 351 Through hole

Claims

1. a mixing device to which a solvent and carbon nanotubes are respectively supplied and in which a mixture of the solvent and the carbon nanotubes is stored; a first dispersing device connected to the mixer, which disperses the carbon nanotubes between a rotor and a stator for primary dispersion, and then disperses the carbon nanotubes by discharging them to the outside through a plurality of through holes on the stator due to the rotational force of the rotor, thereby forming bent sections in the carbon nanotubes; a second dispersing device for selectively cutting the curved sections of the carbon nanotubes by irradiating a laser when the mixture is recirculated to the mixer, and dispersing the carbon nanotubes tertiarily; A system for producing a carbon nanotube dispersion, comprising:

2. The mixing device comprises: a solvent tank in which the solvent is stored; a carbon nanotube tank in which the carbon nanotubes are stored; a mixing tank connected to the solvent tank and the carbon nanotube tank, respectively, for mixing and circulating the solvent and the carbon nanotubes supplied from the solvent tank and the carbon nanotube tank, respectively, via an internal agitator; 2. The carbon nanotube dispersion liquid production system according to claim 1, further comprising:

3. The carbon nanotube tank comprises:

3. The carbon nanotube dispersion manufacturing system according to claim 2, wherein the carbon nanotubes are supplied in a set amount via an automatic feeder.

4. the first dispersion device is connected to the mixing device and includes a storage tank to which the mixed liquid is supplied from the mixing device; the rotor has a rotation axis that is aligned with the inflow direction of the mixed liquid and is disposed at the center of the storage tank so as to rotate in a direction perpendicular to the inflow direction of the mixed liquid; The carbon nanotube dispersion liquid manufacturing system of claim 1, wherein the stator has an open side facing the inflow direction of the mixed liquid and is fixed to the storage tank together with the rotor's driving motor via the other closed side, and a plurality of through holes are formed on the peripheral surface surrounding the rotor.

5. 5. The system for producing a carbon nanotube dispersion liquid according to claim 4, wherein the diameter of the through hole of the stator is set within a range of 20 mm to 200 mm.

6. 2. The system for producing a carbon nanotube dispersion liquid according to claim 1, wherein a distance between the rotor and the stator is set in a range of 10 mm to 500 mm.

7. The second dispersion device is 2. The system for producing a carbon nanotube dispersion liquid according to claim 1, further comprising a laser beam device disposed toward a connecting pipe through which the mixture flows from the first dispersion device to the mixer.

8. The connecting pipe is 8. The carbon nanotube dispersion liquid production system according to claim 7, which is made of optical glass.

9. The amount of energy of the laser irradiated by the laser beam device is 250 mJ / cm ２ More than 600mJ / cm ２ 8. The carbon nanotube dispersion liquid manufacturing system according to claim 7, characterized in that the range is set as follows:

10. 1. A method for producing a dispersion of carbon nanotubes, comprising: A first step of mixing a liquid solvent and the carbon nanotubes in a powder state in a set amount through a mixer to form a mixture; a second step of primarily dispersing the carbon nanotubes by moving the mixture to a first dispersing device and debundling the carbon nanotubes between a rotor and a stator by a rotational force of a rotor of the first dispersing device; a third step of dispersing the first dispersed carbon nanotubes secondarily such that the carbon nanotubes are discharged to the outside through a plurality of through holes on the stator by a rotational force of the rotor, thereby forming bent sections in the carbon nanotubes; a fourth step of selectively cutting the bent sections of the carbon nanotubes by irradiating the bent sections with a laser while the second dispersed carbon nanotubes are passing through a second dispersing device, thereby dispersing the carbon nanotubes thirdly; A method for producing a dispersion liquid of carbon nanotubes, comprising:

11. The first stage comprises: supplying a set amount of the solvent stored in the solvent tank to the mixing tank by operating a motor; supplying a set amount of the carbon nanotubes stored in a carbon nanotube tank to the mixing tank; mixing the solvent and the carbon nanotubes by an agitator in the mixing tank to form the mixture; 11. The method for producing a carbon nanotube dispersion according to claim 10, further comprising:

12. The second stage comprises: moving the mixed liquid from the mixing device to a storage tank of the first dispersing device by a rotational force of a rotor of the first dispersing device; a step of primarily dispersing the carbon nanotubes between the rotor and the stator by debundling the carbon nanotubes as the rotor rotates; 11. The method for producing a carbon nanotube dispersion according to claim 10, further comprising:

13. The third stage is 13. The method for preparing a carbon nanotube dispersion according to claim 12, further comprising a step of secondary dispersion in which the carbon nanotubes are discharged to the outside through a plurality of through holes on the stator by the rotational force of the rotor, thereby forming bent sections in the carbon nanotubes.

14. The fourth stage comprises:

14. The method for preparing a carbon nanotube dispersion liquid according to claim 13, further comprising the step of irradiating a laser to cut the curved sections of the carbon nanotubes when the second dispersion mixture is circulated through the mixer, thereby performing a third dispersion.

15. The fourth stage comprises: Energy amount: 250 mJ / cm ２ More than 600mJ / cm ２ 15. The method for producing a dispersion liquid of carbon nanotubes according to claim 14, characterized in that a laser in the following range is used.

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