KR101601656B1 - The Process Of Producing Carbon Paper - Google Patents

Abstract

The present invention relates to carbon paper, and it is an object of the present invention to provide a carbon paper which is excellent in physical properties such as electrical conductivity and electrical properties such as electrical conductivity and physical properties such as flexibility, .

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a carbon paper,

The present invention relates to a carbon paper excellent in electric characteristics such as electrical conductivity.

Carbon nanotubes (CNTs) have a large aspect ratio (diameter of several tens of nanometers, and a length of several hundreds of micrometers), graphite sheets have nano-sized diameters, cylinders, Depending on the angle and structure, the single walled carbon nanotube (SWCNT), the double walled carbon nanotube (DWCNT), the multiwalled carbon nanotube (MWCNT) And carbon nanotubes (Rope Carbon Nanotube). In addition, the energy band gap varies depending on the dried form and has a quasi one-dimensional structure, thereby exhibiting a unique quantum effect.

These carbon nanotubes have a wide specific surface area due to a very large aspect ratio, and can be used as a high sensitivity sensor because they have a large surface area capable of bonding and reacting with other external materials. Also, they have very strong mechanical properties while being bent. do. In recent years, researches using CNT and carbon fiber paper (CFP, carbon fiber paper) instead of artificial graphite, natural graphite and other carbon materials, which are cathode materials used in lithium secondary batteries, have been actively conducted. Graphite has a theoretical capacity of 372 mAh / g, whereas CNT has a capacity of more than 1400 mAh / g. In the past, ITO (Indium Tin Oxide) has been used as a positive electrode of a solar cell. Recently, a transparent, flexible and bendable electrode material is required according to development of an organic solar cell. However, CNT has not yet reached the level of ITO in terms of electrical conductivity or transparency, but CNT is being mentioned as a material of flexible transparent electrodes in the future.

In order to use the intrinsic properties of CNTs as thin films and membranes, there is a limit to form a large number of CNT aggregates. A CNT aggregate made in the form of a thin sheet is generally called carbon nanotube paper (CNTP). Since CNTP is composed of nanotubes with a diameter of several nanometers, it has a low thickness and high specific surface area, which is a new material that is being applied in various composite materials. A similar new material is CFP (carbon fiber paper), which is produced in a two-dimensional sheet form by laminating randomly arranged carbon fibers. CFP has been applied in various fields due to its many advantages such as excellent mechanical strength, electric conductivity, gas permeability and chemical stability. However, it is difficult to add additional CFP due to impregnation of phenol, epoxy, Stabilization, and carbonization processes are required. Which is disadvantageous in that the manufacturing process is complicated and the production cost is increased.

Korean Patent Laid-Open Publication No. 10-2014-0007729 (published on April 20, 2014)

Therefore, in order to solve the problems of the prior art, the present invention can reduce the manufacturing cost by using carbon nanotubes having excellent electrical characteristics instead of carbon fiber paper, And the like.

Therefore, according to the present invention, there is provided a carbon paper characterized by comprising a carbon nanotube having a length of 300 to 500 mu m and a polyamide flocculating agent.

In addition, the present invention provides a carbon paper characterized by comprising carbon nanotubes having a length of 300 to 500 탆, carbon fibers having a length of 6 to 10 mm, and a polyamide-based coagulant.

In the present invention, a carbon nanotube having a length of 300 to 500 μm is dispersed in water, a polyamide coagulant is added to the dispersion, and the mixture is homogeneously mixed to obtain a slurry. Then, the slurry is supplied to a water- And then hot-pressed at 130 to 150 DEG C after the production.

In addition, in the present invention, carbon nanotubes having a length of 300 to 500 탆 and carbon fibers having a length of 6 to 10 mm are dispersed in water, polyamide coagulant is added to the dispersion, uniformly mixed to obtain a slurry, Slurry is supplied to a water pod to prepare a composite paper, and then hot pressed at 130 to 150 캜.

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

The carbon paper of the present invention is composed of a carbon nanotube and a polyamide-based coagulant having a length of 300 to 500 mu m. The carbon paper of the present invention is composed of carbon nanotubes having a length of 300 to 500 탆, carbon fibers having a length of 6 to 10 mm, and a polyamide-based coagulant.

Known carbon nanotubes are used as the carbon nanotubes. In the present invention, it is preferable that the length of the carbon nanotubes is cut to 300 to 500 mu m when the slurry is prepared. When the carbon nanotubes having a fineness of 0.01 to 0.02 tex are used Good for bonding. The polyamide-based coagulant plays a role of dispersion and agglomeration. The carbon fibers are preferably carbon fibers having a length of 6 to 10 mm. The fibers having a fineness of 0.1 to 0.2 tex are preferable for bonding with carbon nanotubes. It is preferable that the carbon fiber is one of a non-sizing PAN, an epoxy-sizing PAN, and a pitch.

The pore size of the carbon paper is preferably in the range of 3 to 5 mu m for improving electrical characteristics.

Also, in the present invention, it is possible to provide a flexible electrode including the carbon paper, which can greatly improve not only electrical characteristics but also thermal properties.

Hereinafter, the production method of the carbon paper of the present invention will be described in detail.

First, the case of using only carbon nanotubes will be described.

A carbon nanotube having a length of 300 to 500 탆 is dispersed in water and then a polyamide coagulant is added to the dispersion to uniformly mix the mixture to obtain a slurry. The slurry is then fed to a water pod, Lt; 0 > C to produce carbon paper.

It is preferable to disperse carbon nanotubes having a length of 300 to 500 mu m and a fineness of 0.01 to 0.02 tex in water and dispersing while stirring at 1500 to 2500 rpm. When the speed is less than 1500 rpm, the carbon nanotubes do not disperse smoothly, Carbon paper can not be obtained. When the speed exceeds 2500 rpm, there is a problem that the carbon paper is not formed and the torn or short-circuited portions are increased, and the conductivity is lowered. Thereafter, a polyamide-based coagulant is added to the dispersion and uniformly mixed to obtain a slurry.

The polyamide-based coagulant is preferably contained in an amount of 0.5 to 1% by weight relative to the total solid content. In the present invention, by mixing the polyamide flocculating agent with the dispersed carbon nanotubes, the aggregation force and the aggregating force between the dispersed carbon nanotubes are improved to prevent the separation of the carbon nanotubes, thereby improving the physical properties such as strength and electrical conductivity of the carbon paper . When it is mixed at less than 0.5% by weight, the cohesive force and the bonding force of the carbon nanotubes are lowered to lower the physical properties such as strength of the carbon paper. When the carbon nanotubes are mixed at more than 1% by weight, the physical properties such as paper strength are excellent, There is a problem of deterioration.

It is preferable to stir using a stirrer to prevent the aggregation of the polyamide flocculating agent and to obtain a slurry in which the carbon nanotubes are homogeneously dispersed. At this time, it is preferable that the agitation condition through the stirrer is from 60 to 300 seconds at 1500 to 2500 rpm. When the stirring time is less than 60 seconds, the cohesive force and bonding force between the carbon nanotube and the polyamide flocculating agent are lowered, and the physical properties such as paper strength are lowered. When the flocculating time exceeds 300 seconds, have.

Thereafter, the slurry is supplied to a water pod to produce a composite paper, and hot pressed at 130 to 150 ° C to obtain a carbon paper made of carbon nanotubes.

On the other hand, a method of further mixing the carbon fibers is as follows.

Carbon nanotubes having a length of 300 to 500 μm and carbon fibers having a length of 6 to 10 mm are dispersed in water and dispersed while stirring at 1500 to 2500 rpm through a stirrer as in the case of using only the carbon nanotubes . Then, a polyamide coagulant is added to the dispersion to uniformly mix the mixture to obtain a slurry, and the slurry is supplied to a water pod to prepare a composite paper, followed by hot pressing at 130 to 150 ° C to produce carbon paper.

The polyamide-based coagulant is preferably contained in an amount of 0.5 to 1% by weight based on the total solid content of the slurry.

Therefore, according to the present invention, it is possible to provide a uniform carbon paper having excellent physical properties such as electrical conductivity and electrical properties such as electrical conductivity, flexibility and the like because each of the flexible and soft individual carbon nanotubes is formed into one aggregate , The present invention can lower the manufacturing cost by using an inexpensive carbon nanotube. On the other hand, the carbon paper of the present invention can be widely used not only in flexible electrodes but also in other industrial fields such as conductive polymer composites, films and the like.

1 is a photograph of a surface of a carbon paper according to the present invention taken by a field emission scanning electron microscope,
2 is a graph showing the pore size of the carbon paper of Example 1 according to the present invention,
3 is a graph showing the pore size of the carbon paper of Comparative Example 1,
4 is a photograph of a surface of a carbon paper according to Example 1 of the present invention taken by a field emission scanning electron microscope,
5 is a photograph of the surface of the carbon paper of Comparative Example 1 taken by a field emission scanning electron microscope,
FIGS. 6 to 9 are photographs of carbon fiber types of carbon paper according to Examples 2 to 19 according to the present invention, respectively, obtained by scanning electron microscopy of the surface of NON-Sizing PAN, sizing PAN, Lt;
10 is a graph showing electrical conductivity results of the carbon papers of Examples 2 to 19 according to the present invention.

The following examples illustrate non-limiting examples of producing the carbon paper of the present invention.

[Example 1]

Hereinafter, the present invention will be described in more detail with reference to Examples, but the scope of the present invention is not limited to the following Examples.

First, to disperse the carbon nanotubes, the mixture was mixed with water through a colloid mill and treated at 2000 rpm for 120 seconds to carry out dispersion. The carbon nanotubes used were JC-142 products of 300 to 500 μm in length, 8 to 10 nm in thickness, and 99 wt% in purity, produced by JEIO, Inc. of Japan. In order to produce a uniform paper having excellent electrical characteristics, 0.5 wt% of polyamide based coagulant was added to the dispersed carbon nanotubes to prepare a slurry after stirring. Carbon paper was prepared by using a paper making machine. In order to improve the bonding force of CNTs by inducing hydrogen bonding while removing water remaining in the produced carbon paper, hot press equipment (Carver, 12-12H) was used to heat the carbon paper at 130 ° C under 0.03 MPa pressure and 180 sec. The pressing process was carried out.

[Comparative Example 1]

Carbon paper was prepared in the same manner as in Example 1, except that the polyamide-based coagulant was not mixed.

The physical properties of the carbon paper prepared in the above Examples and Comparative Examples were measured, and the results are shown in Table 1 below.

division Example 1 Comparative Example 1 Paper thickness (탆) 94 124 Conductivity (S / cm) 26.48 8.95 Porosity (%) 57 66

[Examples 2 to 7]

Carbon nanotubes and NON-sizing PAN carbon fibers were mixed under the same conditions as in Example 1, as shown in Table 2, to prepare paper. In order to improve the bonding force between CNT and carbon fiber by inducing hydrogen bonding while removing water remaining in the carbon paper, the carbon paper was pressurized at 130 ° C under 0.03 MPa pressure and 180 sec The hot pressing process was carried out. The electrical conductivity and porosity according to the carbon fiber addition were measured for the obtained examples, and the results are shown in Table 2 below.

division Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Carbon nanotube / carbon fiber 95/5 90/10 80/20 60/40 40/60 20/80 Paper thickness (탆) 110 92 81 58 57 52 Conductivity (S / cm) 13.60 17.94 18.43 26.54 29.94 38.99 Porosity (%) 73 68 63 62 57 65

[Examples 8 to 13]

Carbon nanotubes and Sizing PAN carbon fibers were mixed under the same conditions as in Example 1, as shown in Table 3, to prepare paper. The electrical conductivity and porosity according to the carbon fiber addition were measured for the obtained examples, and the results are shown in Table 3 below.

division Example 8 Example 9 Example 10 Example 11 Example 12 Example 13 Carbon nanotube / carbon fiber 95/5 90/10 80/20 60/40 40/60 20/80 Paper thickness (탆) 95 91 89 62 57 57 Conductivity (S / cm) 11.72 12.47 15.40 21.14 25.89 33.66 Porosity (%) 67 64 63 61 58 60

[Examples 14 to 19]

Carbon nanotubes and pitch-based carbon fibers were mixed under the same conditions as in Example 1, as shown in Table 3, to prepare paper. Electrical conductivity and porosity according to the carbon fiber addition were measured for the obtained examples, and the results are shown in Table 4 below.

division Example 14 Example
15 Example 16 Example 17 Example 18 Example 19 Carbon nanotube / carbon fiber 95/5 90/10 80/20 60/40 40/60 20/80 Paper thickness (탆) 106 85 72 60 58 55 Conductivity (S / cm) 12.97 11.83 11.57 11.30 9.15 7.49 Porosity (%) 64 62 59 58 56 51

As shown in Table 1, when the coagulant was added, the electrical conductivity and the porosity were superior to those without the coagulant, and a uniform size paper having a pore size of less than 5 μm was obtained. In Examples 2 to 19, as the carbon fiber content was increased, the thickness decreased and the bulk density increased. As the bulk density increased, the porosity tended to decrease. The electrical conductivity increased with increasing carbon fiber content, but decreased with pitch.

Claims (9)

delete delete delete delete delete The carbon nanotubes having a length of 300 to 500 탆 are dispersed in water and stirred at 1500 to 2500 rpm. Polyamide coagulant is added to the dispersion in an amount of 0.5 to 1% by weight based on the total solid content of the slurry and uniformly mixed to obtain a slurry The slurry is supplied to a water pod to prepare a composite paper, and then hot pressed at 130 to 150 ° C. Carbon nanotubes having a length of 300 to 500 占 퐉 and carbon fibers having a length of 6 to 10 mm are dispersed in water and stirred at 1500 to 2500 rpm and then dispersed in the dispersion to 0.5 to 1% by weight based on the total solids of the slurry, And the mixture is homogeneously mixed to obtain a slurry, and the slurry is supplied to a water pod to prepare a composite paper, and hot-pressed at 130 to 150 ° C. delete delete

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