KR101672318B1

KR101672318B1 - Carbon Nanotube Paste, Method For Manufacturing Thereof And Method For Manufacturing CNT Emitter Using The Same

Info

Publication number: KR101672318B1
Application number: KR1020150000684A
Authority: KR
Inventors: 김대준; 김동일; 박관수
Original assignee: (주) 브이에스아이
Priority date: 2015-01-05
Filing date: 2015-01-05
Publication date: 2016-11-04
Also published as: WO2016111518A1; KR20160084148A

Abstract

The present invention relates to a carbon nanotube paste, a method for producing the carbon nanotube paste, and a method for producing the carbon nanotube emitter using the carbon nanotube paste. The carbon nanotube paste includes graphene for mixing and dispersing carbon nanotubes and carbon nanotubes And an organic binder for adhering a mixture of the carbon nanotubes and the mixed material to the adherend. Accordingly, the carbon nanotube emitter can be directly formed on the large-area negative electrode, and stable dispersion current can be obtained by achieving dispersion with high stability.

Description

Technical Field [0001] The present invention relates to a carbon nanotube paste, a carbon nanotube paste, a method of manufacturing the carbon nanotube paste, and a manufacturing method of the carbon nanotube emitter using the carbon nanotube paste.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon nanotube (CNT) paste, a method of manufacturing the carbon nanotube paste, and a method of manufacturing a carbon nanotube emitter using the carbon nanotube paste. More particularly, A method of manufacturing the carbon nanotube paste, and a method of manufacturing a carbon nanotube emitter using the carbon nanotube emitter.

As display technology has recently developed, flat panel display devices have been widely used instead of conventional cathode ray (CRT) displays. Examples of such flat panel display devices include a liquid crystal display (LCD), a plasma display panel (PDP), and a field emission display (FED).

The field emission is a phenomenon in which electrons are emitted into a vacuum when an electric field is applied to a conductive emitter having a sharp tip formed on a cathode electrode. The display using this principle inherits the merits of a CRT such as a fast response speed and a high image quality, It is evaluated as a next-generation display that drastically improved the disadvantages of CRT in that it can be made thin, light and thin.

On the other hand, carbon nanotubes have advantages such as high aspect ratio, mechanical strength, chemical stability, and high melting point. From the discovery, application as an electron source to various devices such as display, lamp, Principle Emitter provides the best performance.

One of the two methods for fabricating a carbon nanotube emitter for use as a carbon nanotube as an electron source of a device is a method of directly growing a carbon nanotube on a negative electrode and the other is a method of screen printing carbon nanotube paste .

In the case of the direct growth method, there is an advantage such that the density of the carbon nanotube formation of the emitter can be controlled. However, it is difficult to apply to a large-area device due to a cost problem, There is a drawback that the strength is weak.

On the other hand, in the case of the screen printing method of a carbon nanotube paste, it is possible to easily and cheaply form a large-area carbon nanotube on a negative electrode through printing. However, in order to use the carbon nanotube paste as a stable emitter, The binder must be subjected to a complicated step of evaporation and surface treatment of the binder and activation of the emitter as a stable emitter through an aging process that reduces the reduction of the output characteristics.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide a carbon nanotube paste capable of effectively dispersing a field emission device on a negative electrode to achieve stable output and effectively shortening a manufacturing process of an emitter, And a method of manufacturing a carbon nanotube emitter using the same.

A carbon nanotube paste according to an embodiment of the present invention that solves such problems includes a carbon nanotube, a mixed material including graphene for mixing and dispersing the carbon nanotube, and a mixed material containing the carbon nanotube and the mixed material And an organic binder for adhering the resulting mixture to the object.

The carbon nanotube and the mixed material may be mixed in a mass ratio of 1: 1 to 1: 3.

A method of manufacturing a carbon nanotube paste according to an exemplary embodiment of the present invention includes the steps of crushing a mixed material containing graphene, mixing the carbon nanotubes into a crushed mixed material to prepare a mixture, And dispersing the organic binder in an organic binder.

In the step of crushing the mixed material, the mixed material may be crushed to a size of 45 mu m or less through physical force.

In the step of preparing the mixture, the carbon nanotube and the mixed material may be mixed in a mass ratio of 1: 1 to 1: 3.

A method of manufacturing a carbon nanotube emitter according to an exemplary embodiment of the present invention includes the steps of: preparing a carbon nanotube paste including a carbon nanotube, a mixed material containing graphene, and an organic binder; A step of printing and firing the paste on the negative electrode, and a step of applying the carbon nanotube adhered to the graphene and the graphene from the fired carbon nanotube paste to the roller . &Lt; / RTI >

The step of preparing the carbon nanotube paste includes a step of crushing a mixed material containing graphene, a step of mixing the carbon nanotubes into the crushed material to prepare a mixture, and a step of dispersing the mixture in an organic binder .

In addition, in the step of preparing the mixture, the carbon nanotube and the mixed material may be mixed in a mass ratio of 1: 1 to 1: 3.

According to the carbon nanotube paste, the method for producing the carbon nanotube paste, and the method for manufacturing the carbon nanotube emitter using the carbon nanotube paste, carbon nanotube emitters can be produced by mixing the carbon nanotubes with graphene, The nanotubes are directly adhered to the negative electrode, thereby suppressing the decrease in the characteristics of the carbon nanotubes when the field emission is performed and obtaining stable emission characteristics. In addition, when 90% or more of the graphene and the carbon nanotubes adhered to the graphene are removed during the surface treatment, a considerable distance is provided between the residual carbon nanotubes to suppress the electric field screen effect, The electrical stress to be applied to the gate electrode can be reduced and a stable emission characteristic can be obtained. Furthermore, it is possible to easily manufacture a carbon nanotube emitter uniform over a large area by using a roller-based belt conveyor surface treatment apparatus.

1 is a flowchart illustrating a method of manufacturing a carbon nanotube paste according to an embodiment of the present invention.
2 is a flowchart illustrating a method of manufacturing a carbon nanotube emitter according to an embodiment of the present invention.
3 is a view illustrating a surface treatment method of a carbon nanotube emitter according to an embodiment of the present invention.
4 is a graph showing the emission characteristics of the carbon nanotube emitter manufactured by the present invention.

The present invention is capable of various modifications and various forms, and specific embodiments are illustrated in the drawings and described in detail in the text. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprising" or "having ", and the like, are intended to specify the presence of stated features, integers, steps, operations, elements, parts, or combinations thereof, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, parts, or combinations thereof.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the meaning in the context of the relevant art and are to be interpreted as ideal or overly formal in meaning unless explicitly defined in the present application Do not.

Hereinafter, preferred embodiments of the present invention will be described in more detail.

The carbon nanotube paste according to one embodiment of the present invention includes a carbon nanotube, a mixed material for mixing and dispersing the carbon nanotube, and a mixture of the carbon nanotube and the mixed material, And an organic binder.

The nanomaterials such as the carbon nanotubes have a property of recombining (lumping) after a predetermined period of time has elapsed after dispersion. If such a carbon nanotube paste is used as it is in the manufacture of an emitter, the density of the carbon nanotubes Resulting in nonuniformity of field emission characteristics.

Therefore, a solid mixed material is added to the carbon nanotube paste in order to maintain the stable mixing and dispersion characteristics of the carbon nanotubes until the emitter is manufactured.

The mixed material is composed of a mixture containing graphene or graphene as a main component. The graphene is a thin plate-like nano material in which carbon atoms are intertwined in a honeycomb shape. The graphene has a remarkably low adhesion property to neighboring nano powders as compared with other nano powders. Therefore, by adding the graphene to the carbon nanotube paste, the recombination of the carbon nanotubes can be effectively prevented, and the mixing and dispersion characteristics of the carbon nanotubes can be improved.

The mixed material containing graphene is added in a ratio of about 1: 1 to 1: 3 on a mass basis in comparison with the carbon nanotubes. If the specific gravity of the mixed material occupied in the carbon nanotube paste is too small, the mixing and dispersing characteristics of the carbon nanotubes are deteriorated. On the other hand, if the specific gravity of the mixed material is too large, the density of the carbon nanotubes becomes too small, and the field emission characteristic of the emitter is deteriorated. Therefore, it is preferable that the mixed material is mixed at a mass ratio of about 1: 1 to 1: 3 in consideration of the mixing and dispersion characteristics of the carbon nanotubes and the field emission properties of the emitter.

The organic binder serves to impart a viscosity such that a mixture of the carbon nanotubes and the mixed material is adhered to an adherend such as a negative electrode of an emitter. The viscosity of the carbon nanotube paste can be controlled by adjusting the mixing amount of the organic binder.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

1 is a flowchart illustrating a method of manufacturing a carbon nanotube paste according to an embodiment of the present invention.

Referring to FIG. 1, a method of manufacturing a carbon nanotube paste according to an embodiment of the present invention includes the steps of crushing a mixed material containing graphene (S12), mixing the carbon nanotubes with the crushed material, (S14), and dispersing the mixture in an organic binder (S16).

In the step (S12) of crushing the mixed material, the graphene of the plate structure is crushed to a suitable size to improve the mixing property with the carbon nanotubes. If the size of the graphene is too large, the ability to mix with the carbon nanotubes may be deteriorated. Therefore, it is preferable that the graphene is crushed to a size of about 45 μm or less in order to enhance the mixing property with the carbon nanotubes.

The graphene crushing method is preferably a physical crushing method in order to prevent performance deterioration due to chemical crushing. For example, physical pulverization of graphene can be performed by adding beads to the graphene of the raw material and rotating it. At this time, the size of the graphene to be crushed can be adjusted by adjusting the amount of beads to be added, the rotation speed, and the like.

After crushing the mixed material, carbon nanotubes are mixed with the crushed mixed material to form a mixture (S14). At this time, the carbon nanotubes and the mixed material are mixed at a mass ratio of about 1: 1 to 1: 3 in order to improve the mixing and dispersion characteristics of the carbon nanotubes and the field emission properties of the emitters produced thereby .

Next, the mixture in which the graphene and the carbon nanotubes are mixed is dispersed in an organic binder to prepare a carbon nanotube paste having a predetermined viscosity (S16). At this time, the viscosity of the carbon nanotube paste can be controlled by adjusting the mixing amount of the organic binder.

On the other hand, the carbon nanotube paste manufactured through the above-described manufacturing method can be used for field emission emitters and the like.

FIG. 2 is a flowchart illustrating a method of manufacturing a carbon nanotube emitter according to an embodiment of the present invention, and FIG. 3 is a view illustrating a surface treatment method of a carbon nanotube emitter according to an embodiment of the present invention.

2 and 3, a method of manufacturing a carbon nanotube emitter according to an embodiment of the present invention includes: preparing a carbon nanotube paste including a carbon nanotube, a mixed material including graphene, and an organic binder; (S20) of printing and firing the carbon nanotube paste on the negative electrode (100), and a surface treatment apparatus (400) including a roller (410), the carbon nanotube paste And a step S30 of surface-treating the surface of the negative electrode 100 fired.

The step (S10) of producing the carbon nanotube paste includes the steps of crushing a mixed material containing graphene, mixing the carbon nanotubes with the crushed material to prepare a mixture, and dispersing the mixture in an organic binder .

The carbon nanotube paste manufacturing method according to this embodiment is substantially the same as that of the carbon nanotube paste manufacturing method shown in FIG. 1, and a detailed description related thereto will be omitted.

Next, the carbon nanotube paste, which has been manufactured, is screen-printed on a cathode electrode 100 for manufacturing a carbon nanotube emitter, and then the carbon nanotube paste is fired by heating to a predetermined temperature (S20) . 3 (a), the carbon nanotubes 200 and the graphene 300 are formed on the negative electrode 100 through the firing process of the carbon nanotube paste.

Next, the fired carbon nanotube paste is subjected to a surface treatment process using a surface treatment apparatus 400 (for example, a belt conveyor surface treatment apparatus of a roller substrate) including a roller 410 (S30 ).

The surface treatment process proceeds in such a manner that the roller 410 is brought into contact with the fired carbon nanotube paste at a constant speed and pressure through driving of a belt conveyor of the surface treatment apparatus 400.

Since the graphene 300 has a plate-like structure and the adhesion with surrounding molecules is remarkably low, the graphene 300 is formed by 90% or more of the graphene 300 and a part of the carbon The nanotube 200 is removed by adhesion with the roller 410. [ On the other hand, the carbon nanotube 200 remaining after the surface treatment is directly adhered to the negative electrode 100 as shown in FIG. 3 (b), while the effect of the electric field screen is suppressed between the carbon nanotubes 200 A significant distance is formed.

4 is a graph showing the emission characteristics of the carbon nanotube emitter manufactured by the present invention.

Referring to FIG. 4, the carbon nanotube emitter manufactured according to an embodiment of the present invention was subjected to aging treatment at 400 V and 2.5 mA for 30 minutes. As a result, field emission of the carbon nanotube emitter It can be confirmed that the current drop is hardly generated at the time of sustain.

As described above, by preparing the carbon nanotube emitter with the nanocarbon based mixture in which carbon nanotubes and graphene are mixed, the carbon nanotubes are directly adhered to the negative electrode during the surface treatment, and the characteristics of the carbon nanotubes in the field emission are reduced And stable emission characteristics can be obtained. It is also possible to remove carbon nanotubes adhered to graphene by 90% or more of the graphene during the surface treatment to give a considerable distance between the remaining carbon nanotubes to suppress the electric field screen effect, The electrical stress to be applied to the gate electrode can be reduced and a stable emission characteristic can be obtained. Furthermore, it is possible to easily manufacture a carbon nanotube emitter uniform over a large area by using a roller-based belt conveyor surface treatment apparatus.

While the present invention has been described in connection with what is presently considered to be practical and exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention. Accordingly, the foregoing description and drawings are to be regarded in an illustrative rather than a restrictive sense of the invention.

100: negative electrode 200: carbon nanotube
300: Graphene 400: Surface treatment device
410: Roller

Claims

delete

Adding beads to the plate-like graphene and rotating it to physically break the graphene;
Mixing the crushed graphene with carbon nanotubes to prepare a mixture; And
Dispersing the mixture in an organic binder,
Wherein the carbon nanotube and the graphene are mixed at a mass ratio of 1: 1 to 1: 3.

The method of claim 3,
Wherein the graphene is crushed to a size of 45 mu m or less through physical force in the step of crushing the graphene of the plate structure.

delete

Physically disrupting graphene by adding beads to the graphene;
Mixing the crushed graphene with carbon nanotubes to prepare a mixture;
Dispersing the mixture in an organic binder to prepare a carbon nanotube paste;
Printing and firing the carbon nanotube paste on a negative electrode; And
And removing the carbon nanotubes adhering to the graphene and the graphene from the fired carbon nanotube paste by adhesion with the roller by using a surface treatment apparatus including a roller,
Wherein the carbon nanotubes and the graphene are mixed in a mass ratio of 1: 1 to 1: 3 in the step of preparing the mixture.

delete

The method according to claim 6,
Wherein the graphene is crushed to a size of 45 mu m or less through physical force in crushing the graphene of the plate structure.

delete