KR101071688B1 - Method and Devices for Carbon Nanotube Cutting-Dispersion - Google Patents

Abstract

Carbon nanotubes have a length of 500 to 1000 times longer than their diameters due to their physical properties, so that a plurality of carbon nanotubes exist in a tangled aggregate state. The present invention relates to a method and apparatus for inducing a collision between a carbon nanotube aggregate and a fixed object or a moving object, and mutual collision between the entangled carbon nanotube aggregates so that the carbon nanotubes are cut and dispersed by their impact energy. . The present invention can significantly solve the problem of deterioration of physical properties of the carbon nanotubes and the generation of foreign substances in the process of cutting the carbon nanotubes.

Carbon nanotubes, cutting, dispersion, impact energy, collision

Description

Carbon nanotube cutting dispersion method and apparatus {Method and Devices for Carbon Nanotube Cutting-Dispersion}

According to the present invention, carbon nanotube (CNT) aggregates are collided with a wall or a mover, or carbon nanotubes are cut at the collision part by mutual collisions between carbon nanotube aggregates, and tangled carbon nanotubes are dispersed. The carbon nanotube aggregate dispersion and carbon nanotube structure length reduction effect is exhibited, the carbon nanotube structure is damaged in the process of the carbon nanotube structure is damaged in order to minimize the deterioration of physical properties or foreign matter generation A method and apparatus are disclosed.

Carbon nanotubes can be synthesized up to several tens of micrometers in length with a diameter in the range of 1 ~ 200nm. In the process of synthesizing carbon nanotubes using a thermochemical vapor deposition method or an arc discharge method, physical and chemical aggregation occurs between individual carbon nanotube particles. The physical agglomeration is carbon nanotubes entangled and wound with other particles as individual particles at the micrometer level, and the chemical agglomeration is caused by surface forces such as Van der waals force, which is an intermolecular force at the nanometer level. It is aggregated by. Such agglomeration of carbon nanotubes prevents the formation of a three-dimensional network structure that can improve the mechanical strength and conduction properties of carbon nanotubes. In addition, due to the cohesion phenomenon between the carbon nanotubes, the adhesion between the polymer matrix and the carbon nanotube interface is insufficient, so that the external load generated in the matrix cannot be sufficiently transferred to the carbon nanotubes. Therefore, in order to fully exhibit the physical and chemical characteristics of the carbon nanotubes, it is urgently required to minimize the length of the carbon nanotubes and to develop a dispersion method without deteriorating physical properties.

Conventional carbon nanotube cutting dispersion method is as follows. Meanwhile, the term "dispersion" used hereinafter refers to "phenomena in which carbon nanotube aggregates are physically cut or chemically treated to reduce the volume and length of the aggregates, or entangle the carbon nanotube aggregates to dissociate and disperse them." It is used to mean in advance.

1. Ball Milling Method

As a method of minimizing the length of the carbon nanotubes by using ball milling, this has the effect of reducing the length of the carbon nanotubes, but there is a disadvantage that the physical properties are deteriorated due to the enormous damage of the nanostructure due to the ball milling.

2. Ultrasonic Treatment

Carbon nanotubes are dispersed in a solvent such as alcohol by ultrasonication, and carbon nanotubes are bent or buckled during the cutting of the length, causing enormous damage to the nanostructures. The recombination of the nanotubes has the disadvantage that the size of the bundle is increased.

3. Method by polishing

The polishing process is more destructive than other methods, and in order to reduce damage by this process, α-cyclodextrin or β-cyclodextrin solvent is put together with carbon nanotubes in a mortar and chemically cut through the polishing process. Due to this, the length and bundle thickness of the carbon nanotubes can be significantly reduced, but this polishing method also has the disadvantage of serious damage to the carbon nanotubes themselves.

4. Solvent Method

Dispersion by solvents has the disadvantage of being unstable over time because it can be explained by the mechanism by solution. Solubility is very low for various solvents that are generally used in solution process. There is.

The above-described carbon nanotube dispersion methods cause serious damage to the carbon nanotube structure in the dispersion process, and their physical properties are deteriorated, and carbon nanotube polymer composites, conductive composites, ultralight, ultra-high strength, It is an obstacle to commercialization of high heat resistant composite materials.

In order to express the physical and chemical properties of carbon nanotubes, carbon nanotube cutting and dispersing technology that minimizes the length of carbon nanotubes is urgently required. Non-tubular metal particles have a relatively similar ratio of length (thickness) to diameter, so that they are uniformly and well deposited on the base material (metal and nonmetal), whereas carbon nanotubes have a tube shape (diameter: length = 1: 500 ~ 1000) are entangled, there are many problems that are difficult to uniformly deposit on the base material. In addition, depositing (printing) carbon nanotubes in the form of a paste has a disadvantage in that adhesion between the base material and the paste is weak and high surface resistance due to poor dispersion of carbon nanotubes. On the other hand, composites made by mixing carbon nanotubes and polymers are hindered in commercialization due to deterioration of expected physical and chemical properties due to poor dispersion of carbon nanotubes. In order to solve the above problems, various studies have shown partial effects in reducing the length of carbon nanotubes and reducing the coagulation phenomenon, but the carbon nanotube structure is severely damaged during the treatment process, which leads to deterioration of physical properties. Doing so is experiencing technical difficulties. Accordingly, an object of the present invention is to provide a cutting dispersion method and apparatus for minimizing the length of carbon nanotubes and reducing the volume of entangled bundles and at the same time minimizing damage to the carbon nanotube structure generated during the dispersion process. .

In order to solve the above problems, the present invention provides a method and apparatus for cutting dispersion by applying impact energy to the carbon nanotube aggregate.

The method of applying impact energy to the carbon nanotube aggregates includes 1) colliding the carbon nanotube aggregates with other objects, 2) colliding the other objects with the carbon nanotube aggregates, and 3) colliding the moving carbon nanotube aggregates with each other. It is possible to consider a method to make, and the present invention can utilize all three of the above methods.

In addition, trace impurities are detected in the process of colliding and dispersing the carbon nanotube aggregates, which is attributable to an object collided with the carbon nanotube aggregates. Therefore, in the present invention, by coating the target object colliding with the carbon nanotube aggregates with carbon nanotubes, even if micro debris is generated by the collision, the micro debris can also minimize the generation of impurities of other components.

Carbon nanotube cutting and dispersing method according to the present invention can be carried out in a vacuum state or atmospheric pressure, it can be carried out at room temperature. According to the present invention 1) high dispersion of carbon nanotube aggregates (high dispersion), and 2) the present invention can minimize the electrical damage (defect) of the carbon nanotubes despite the mechanical cutting dispersion method, the field emission is It is easy, and there is an effect of improving the control of the sheet resistance and electrical conductivity, strength, durability. 3) In addition, there is no chemical damage of carbon nanotubes because no dispersion solvent is used. 4) The chemical dispersion method takes several tens of hours, whereas the present invention is made within a few minutes. Very short

The carbon nanotubes thus cut and dispersed are 1) solid particles themselves, which can be deposited in the form of an aerosol on the surface of the substrate, regardless of the type of base material such as glass, plastic, metal, etc. 3) A mixed liquid solution made by mixing carbon nanotube solid particles cut into a liquid solution containing components that can be adhered to the base material, and deposited on the surface of the base material by printing, stamping, or spraying regardless of the type of base material. Can be. In other words, transparent electrodes, semiconductor wiring, field emission devices, electromagnetic shielding, electrostatic dispersing materials, backlight units, lighting devices, flexible display devices, solar cells, sensors, polymer composites, conductive composites, ultra-lightweight, ultra-high strength and high heat resistance composite materials Applicable

The present invention provides a method of cutting and dispersing carbon nanotubes, which are cut by impact energy by injecting a solid state of carbon nanotube aggregates and colliding with the chamber inner wall. This can be done at room temperature regardless of vacuum or atmospheric pressure, and the carbon nanotubes are cut and the volume and size of the tangled carbon nanotube aggregates are reduced by applying impact energy to the carbon nanotube aggregates. Hereinafter, the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a conceptual diagram of a process of cutting and dispersing carbon nanotube aggregates by colliding with an inner wall of a chamber. In the present invention, by injecting the carbon nanotube aggregate into the chamber inner space 36, the carbon nanotubes that are cut after the impact on the inner wall of the chamber is accommodated in the chamber, for this purpose; And an injector for injecting carbon nanotubes into the chamber; It provides a carbon nanotube cutting dispersion device, characterized in that configured to include. At this time, the injection rate of the carbon nanotube aggregate is controlled at a rate lower than the deposition threshold speed at which carbon nanotubes begin to be deposited on the inner wall of the chamber or at a low deposition efficiency so that the carbon nanotubes receive sufficient impact energy to cut and disperse the carbon nanotubes. It is desirable to minimize the possibility of deposition on the inner wall of the chamber.

FIG. 2 is a conceptual view of cutting and dispersing carbon nanotube aggregates by colliding with moving objects (movers), and installing carbon nanotube aggregates injected into the chamber by mounting and operating a mover 34 in the chamber. The collision rate and cutting rate can be increased. The exerciser 34 may be mounted to rotate in the chamber by electric power, and the rotational speed, the number of installations, and the rotational direction of the exerciser may be adjusted as necessary. On the other hand, in order to prevent the carbon nanotubes from hitting the chamber inner wall and the mover to generate impurities (materials generated from the chamber inner wall or the mover), the chamber inner wall and the mover may be coated with carbon nanotubes. In this case, since the fine particles generated by the collision are also carbon nanotube fragments, they can no longer be treated as impurities. On the other hand, when the carbon nanotube coating is not applied to the inner wall of the chamber and the mover, foreign matters may be filtered from the dispersed carbon nanotubes in the chamber and used as a deposition material.

3 is a conceptual diagram of cutting and dispersing carbon nanotube aggregates by mutual collision. This is a method of cutting and dispersing carbon nanotubes, which is characterized by increasing the collision rate and the cutting rate of carbon nanotubes by simultaneously spraying carbon nanotube aggregates from one or more points toward a point inside the chamber. It is provided with two or more, it can be implemented by the carbon nanotube cutting dispersion device characterized in that the injected carbon nanotube aggregate is controlled to collide with each other in the chamber. The speed of the carbon nanotubes injected from the plurality of injectors may be the same, but may be different from each other. As the spraying method, a direct spraying method through a nozzle, a method of putting carbon nanotubes in a separate container and spraying carbon nanotubes in an aerosol state through a transfer gas is effective. When taking a method of directly injecting carbon nanotube aggregates at high pressure through the nozzle, the inside of the chamber may be controlled at atmospheric pressure, and the inside of the chamber is controlled in a vacuum state when taking a method of injecting carbon nanotubes in an aerosol state. It is desirable to.

4 is a conceptual diagram of an embodiment of a carbon nanotube cutting and dispersing apparatus according to the present invention. 4 shows a method of colliding carbon nanotube aggregates with another object (chamber inner wall), 2) colliding another object (movement) with carbon nanotube aggregates, and 3) motion. As a device for implementing a method of colliding carbon nanotube aggregates in one device, the above three methods are configured to proceed separately. However, the technical idea of the present invention is not limited to the above-described embodiment, and may be implemented in various ways without departing from the technical idea of the present invention specified in the claims. That is, the carbon nanotube cutting and dispersing apparatus may be configured and controlled to perform the respective methods under atmospheric pressure or vacuum, and to perform the methods together as a whole. All matters concerning arrangement and driving sequence are included in the technical idea of the present invention.

1 is a conceptual diagram of a process of cutting and dispersing carbon nanotubes by impinging on an inner wall of a chamber.

2 is a conceptual diagram of cutting and dispersing carbon nanotubes by colliding with a moving object (movement).

3 is a conceptual diagram of cutting and dispersing carbon nanotubes by mutual collision.

4 is a conceptual diagram of an embodiment of a carbon nanotube cutting and dispersing apparatus according to the present invention.

5 is a schematic diagram of cutting at carbon nanotube particles and a collision part.

<Description of the symbols for the main parts of the drawings>

10: carbon nanotube 11: impact part

20: carbon nanotube cutting part 31: carbon nanotube before cutting dispersion

32: cut dispersed carbon nanotube 33: chamber inner wall

34: exerciser 35: chamber

36: chamber internal space 40: injector

Claims (8)

A method of cutting and dispersing carbon nanotubes by spraying carbon nanotube aggregates in a solid state to impinge on the inner wall of a chamber so as to be cut by impact energy. In claim 1, And a collision rate and a cutting rate of the carbon nanotube aggregates injected into the chamber by raising and operating a mover in the chamber. In claim 1, A method of cutting and dispersing carbon nanotubes, comprising: simultaneously imparting carbon nanotube aggregates to one point within a chamber at two or more points, thereby increasing the collision rate and the cutting rate of the carbon nanotube aggregates. delete chamber; And An injector for injecting carbon nanotube aggregates in a solid state into the chamber; Carbon nanotube cutting dispersion device characterized in that comprises a. The method of claim 5, An exerciser mounted in the chamber and rotating by electric power; Carbon nanotube cutting dispersion device further comprising a. In claim 6, Carbon nanotube cutting dispersion device, characterized in that the inner wall of the chamber and the movement is coated with carbon nanotubes. The method according to any one of claims 5 to 7, The injector is provided with two or more, carbon nanotube cutting dispersion device characterized in that the injected carbon nanotube aggregate is controlled to collide with each other in the chamber.

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