KR101534298B1 - a composition for electro-magnetic interference shielding film, a method of fabricating a electro-magnetic interference shielding film therewith and an electro-magnetic interference shielding film fabricated thereby - Google Patents

Abstract

The present invention relates to a composition for an electromagnetic interference shielding film having excellent dispersion stability of a carbon nanotube, a manufacturing method of an electromagnetic interference shielding film having an excellent electromagnetic interference shielding effect using the same, and an electromagnetic interference shielding film manufactured thereby. The composition for an electromagnetic interference shielding film of the present invention comprises water, cellulose-based polymer, and a carbon nanotube. According to the present invention, the dispersion having a polymer-carbon nanotube composite in which a polymer is wrapped around the carbon nanotube, uniformly dispersed therein is used, and a conventional acid treatment process is not used, thereby preventing performance degradation of electromagnetic interference shielding caused by surface damage of the carbon nanotube. Also, the electromagnetic interference shielding film having excellent performance of electromagnetic interference shielding and having the carbon nanotube which has flexibility and thin thickness, can be manufactured even if the composition of the present invention is applied onto a substrate for one time. Furthermore, the film of the present invention exhibits resilience in which the film is restored to the dispersion containing a carbon nanotube-polymer composite if allowing the film to be partly cut and to be dispersed in water, since the film is manufactured based on an aqueous polymer, and dispersibility of the restored dispersion is also excellent.

Description

A composition for an electromagnetic wave shielding film, a method for manufacturing an electromagnetic wave shielding film using the same, and an electromagnetic wave shielding film produced by the method and a method of fabricating an electro-magnetic interference shielding film, interference shielding film fabricated thereby.

TECHNICAL FIELD The present invention relates to a composition for an electromagnetic wave shielding film, a method for manufacturing an electromagnetic wave shielding film using the composition, and an electromagnetic wave shielding film produced thereby. More particularly, the present invention relates to a composition for an electromagnetic wave shielding film excellent in dispersion stability of carbon nanotubes, Shielding film, and an electromagnetic wave shielding film produced thereby.

Techniques for adding an electromagnetic shielding property to a polymer material include adding an inorganic material or a carbon-based material capable of shielding electromagnetic waves to the polymer resin. However, recently, a small amount of carbon nanotubes are added to a polymer resin, Studies are underway to satisfy both shielding performance and moldability

Carbon nanotubes have high electrical conductivity, thermal stability, tensile strength and resilience, so they are used as additives for various composites. When carbon nanotubes are used as an additive for a composite material, how uniformly the bundles of carbon nanotubes are dispersed is a very important factor. The carbon nanotubes have a relatively long length and a strong attraction force between the carbon nanotubes, and thus have a very low dispersion degree to the polymer. One of the conventional techniques for solving this problem is a technique for increasing the degree of dispersion of carbon nanotubes by impregnating carbon nanotubes in nitric acid, sulfuric acid, or a mixed solution thereof to oxidize the surface. However, this technique has various problems such as safety problems or environmental problems because the acid solution is used in the production process, and it is difficult to ensure process stability in mass production.

Korean Patent Publication No. 10-2009-0021056 (Feb. 27, 2009)

The present invention provides a method for preparing a dispersion of carbon nanotubes and polymers by uniformly dispersing the carbon nanotubes and a polymer having excellent dispersibility and electrical conductivity.

Further, the dispersion is coated on a surface-treated substrate and then dried in a vacuum oven to produce a thin film having excellent electromagnetic wave shielding effect, thereby completing the light weight, which is a disadvantage of the existing electromagnetic wave shielding film, And an electromagnetic wave shielding film.

According to an aspect of the present invention, there is provided a method for producing a carbon nanotube, the method comprising: mixing water, a cellulose polymer, and a carbon nanotube, wherein the content of the cellulose polymer is 0.1 to 5 parts by weight based on 100 parts by weight of the water; May be 0.1 to 5 parts by weight based on 100 parts by weight of the water.

In this aspect, the cellulose-based polymer and the carbon nanotube form a complex, and the composite may have a structure in which the cellulose-based polymer surrounds the surface of the carbon nanotube.

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In this aspect, the weight ratio of the cellulose-based polymer to the carbon nanotube may be 1: 1 to 1: 5.

In this aspect, the cellulose-based polymer may be selected from the group consisting of Methyl Cellulose, Hydroxy Ethyl Cellulose, Hydroxy Propyl Methyl Cellulose, Hydroxy Ethyl Methyl Cellulose, And may include at least one member selected from the group consisting of methyl ethyl cellulose, carboxy methyl cellulose, and hydroxy propyl cellulose.

Another aspect of the present invention includes a step of preparing a polymer solution by dissolving a cellulose-based polymer in water, and a step of adding a carbon nanotube to a polymer solution and ultrasonic dispersion to prepare a dispersion containing the carbon nanotube-polymer complex 0.1 to 5 parts by weight based on 100 parts by weight of the water, and 0.1 to 5 parts by weight of the carbon nanotubes based on 100 parts by weight of the water is used as the cellulose-based polymer. .

In this aspect, after the step of providing the dispersion, the method may further include a step of applying and drying the dispersion on the substrate.

In this aspect, examples of the cellulose-based polymer include cellulose derivatives such as methyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl methyl cellulose, At least one selected from the group consisting of methyl ethyl cellulose, carboxy methyl cellulose, and hydroxy propyl cellulose can be used.

In this aspect, the ultrasonic dispersion can be performed using a horn type or bath type ultrasonic dispersion apparatus equipped with a bubbling apparatus.

In this aspect, the weight ratio of the cellulose-based polymer to the carbon nanotube may be 1: 1 to 1: 5.

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Another aspect of the present invention may be an electromagnetic wave shielding film produced according to the method of the foregoing aspect.

According to the present invention, since a dispersion in which a polymer-carbon nanotube composite in which a polymer is wrapped by carbon nanotubes is uniformly dispersed is used and a conventional acid treatment process is not used, the surface of the carbon nanotube It is possible to prevent deterioration of the electromagnetic wave shielding performance due to the electromagnetic wave shielding effect.

Further, even when the composition for electromagnetic wave shielding film according to the present invention is coated once on a substrate, an electromagnetic wave shielding film containing carbon nanotubes having excellent electromagnetic wave shielding performance, flexibility, and thin thickness can be produced.

In addition, although the conventional electromagnetic wave shielding film uses an expensive material such as gold or silver and manufactures an electromagnetic wave shielding film through a complicated process, in the present invention, the content of carbon nanotube and polymer can be easily controlled, The manufacturing cost can be reduced and the productivity can be improved.

In addition, since the electromagnetic wave shielding film according to the present invention is based on a water-soluble polymer, when the film is partially cut and dispersed in water, the electromagnetic wave shielding film has a restoring force to return to a dispersion containing the carbon nanotube-polymer complex. Dispersibility is also excellent.

1 is a schematic view of a structure of a carbon nanotube-polymer composite according to an embodiment of the present invention.
2 is a flowchart illustrating a manufacturing process of an electromagnetic wave shielding film according to an embodiment of the present invention.
3 is a schematic diagram of an ultrasonic dispersing apparatus used in an embodiment of the present invention.
4 is a transmission electron micrograph of a polymer-carbon nanotube composite dispersed in a dispersion prepared according to an embodiment of the present invention.
5 is a photograph of an electromagnetic wave shielding film manufactured according to an embodiment of the present invention.
6 is a scanning electron microscope (SEM) image of a cross section of an electromagnetic wave shielding film manufactured according to an embodiment of the present invention.
7 is a graph showing the electromagnetic wave shielding efficiency of the electromagnetic wave shielding film produced according to Examples and Comparative Examples.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below. Furthermore, embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art. Accordingly, the shapes and sizes of the elements in the drawings may be exaggerated for clarity of description, and the elements denoted by the same reference numerals in the drawings are the same elements.

The present invention relates to a composition for an electromagnetic wave shielding film excellent in dispersion stability, a method for producing an electromagnetic wave shielding film excellent in electromagnetic wave shielding effect using the composition, and an electromagnetic wave shielding film produced thereby.

One aspect of the present invention may be a composition for an electromagnetic wave shielding film comprising water, a cellulose-based polymer, and a carbon nanotube.

This aspect is characterized in that water is used as a solvent and a cellulose-based polymer is used as a water-soluble polymer. Unlike the prior art, water is used as a solvent rather than an organic solvent (toluene and the like). Therefore, it is environmentally friendly, and a complicated process for removing an organic solvent is not required, which simplifies the process and improves the process efficiency.

As the polymer, though not limited thereto, a cellulosic polymer which is an environmentally friendly and water-soluble polymer can be used. Examples of such cellulosic polymers include cellulose derivatives such as methyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl methyl cellulose, methyl ethyl cellulose, At least one selected from the group consisting of cellulose, methyl ethyl cellulose, carboxy methyl cellulose, and hydroxy propyl cellulose can be used. In particular, it is preferable to use Carboxy Methyl Cellulose which is excellent in chemical stability and excellent in durability as a polymer binder.

The content of the cellulose-based polymer may be 0.1 to 5 parts by weight based on 100 parts by weight of water. When the content of the polymer is less than 0.1 parts by weight, the dispersibility of the carbon nanotubes is deteriorated, so there is a problem in the production of a shielding film. When the content is more than 5 parts by weight, the conductivity is deteriorated and there is a problem in electromagnetic shielding performance.

Carbon nanotubes are conductive particles that make the entire composite conductive and improve the mechanical strength. Carbon nanotubes are long tube-like in diameter and have a large interaction between individual carbon nanotubes, so they are likely to exist in a coagulated form in a solution in which the polymer is dissolved. Ultrasonic waves are used to separate the aggregated carbon nanotubes. The ultrasonic waves are applied to a solution in which the carbon nanotubes are dispersed in the form of a horn, a bass, or a mixture thereof, and the carbon nanotubes agglomerated by the ultrasonic waves can be uniformly dispersed in the solution. In the present invention, a horn type or a bath type ultrasonic dispersing apparatus equipped with a bubbling apparatus as an ultrasonic dispersing apparatus is used, whereby the dispersibility can be further improved. The ultrasonic dispersing apparatus used here shall be described in the following section. Ultrasonic dispersion can be performed for 30 minutes to 180 minutes.

The content of the carbon nanotubes may be 0.1 to 5 parts by weight based on 100 parts by weight of water. When the content of the carbon nanotubes is less than 0.1 part by weight, the content of the carbon nanotubes is too small to have sufficient electromagnetic shielding performance. When the content of the carbon nanotubes is more than 5 parts by weight, the viscosity of the solution is high and the dispersion of the carbon nanotubes by the ultrasonic waves is uniform it's difficult. Although the composition of this aspect contains a small amount of carbon nanotubes, the electromagnetic wave shielding film produced using the carbon nanotubes is one of the main features that the electromagnetic wave shielding performance is excellent. Carbon nanotubes are used in various fields because they have high electrical conductivity, excellent thermal stability, high tensile strength and excellent stability. As the carbon nanotubes, multi-wall carbon nanotubes (MWCNTs), single-wall carbon nanotubes (SWCNTs) or mixtures thereof can be used. For cost considerations, it is preferable to use multi-wall carbon nanotubes.

The weight ratio of the cellulose-based polymer to the carbon nanotubes is preferably 1: 1 to 1: 5. One of the main characteristics is that the weight ratio of cellulose polymer to carbon nanotube is almost the same. This is because the cellulose-based polymer can be used only for wrapping and dispersing carbon nanotubes.

A cellulose-based polymer and a carbon nanotube may form a complex (hereinafter, referred to as a 'carbon nanotube-polymer complex'). The carbon nanotube-complex may be a structure in which the cellulose-based polymer surrounds the surface of the carbon nanotube. FIG. 1 shows a schematic view of a structure of a carbon nanotube-polymer complex. Because of this structure, the dispersibility of carbon nanotubes in the dispersion is excellent.

2 shows a process for producing an electromagnetic wave shielding film according to the present invention. Referring to FIG. 2, another aspect of the present invention provides a method for preparing a carbon nanotube-polymer composite, comprising: (S1) preparing a polymer solution by dissolving a cellulosic polymer in water; (S2) of providing a dispersion containing an antistatic agent.

First, the polymer solution may be prepared by dissolving the cellulose-based polymer in water (S1). Water is used as a solvent, and a cellulose-based polymer is used as a water-soluble polymer, and the matters related thereto are the same as those described in the foregoing aspects.

Examples of the cellulose-based polymer include cellulose derivatives such as methyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl methyl cellulose, methyl ethyl cellulose, Methyl Ethyl Cellulose, Carboxy Methyl Cellulose, and Hydroxypropyl Cellulose. In particular, carboxymethylcellulose (Carboxy Methylcellulose) having excellent chemical stability and excellent durability can be used. Methyl cellulose) is preferably used.

The cellulosic polymer may be used in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of water.

Next, the carbon nanotubes are put into the polymer solution and ultrasonically dispersed to prepare a dispersion containing the carbon nanotubes-polymer complex (S2).

As the ultrasonic dispersing device, a horn type or a bath type ultrasonic dispersing device equipped with a bubbling device can be used, thereby further improving the dispersibility. FIG. 3 shows a horn-type ultrasonic dispersing device equipped with a bubbling device. Referring to Fig. 3, the dispersing device may include a dispersion bath 8, a micro bubble generator 1, and an ultrasonic generator 2, 3. The dispersion tank 8 may consist of a body 6 and a lid 7. The micro bubble generator 1 may be positioned at the center of the lid 7 and the plurality of ultrasonic horns 2 and 3 may be positioned around the micro bubble generator. The plurality of ultrasonic horns 2 and 3 are preferably arranged to be symmetrical to each other. The ultrasonic horn is connected to an ultrasonic vibrator (not shown) and amplifies ultrasonic waves generated from the ultrasonic vibrator. Cavitation occurs in the dispersion liquid (or solvent) due to the ultrasonic waves amplified by the ultrasonic horns 2 and 3. This cavitation phenomenon is further amplified by the bubble generated in the micro bubble generator 1, Also, stirring effect can be obtained. Through such ultrasonic dispersion, a carbon nanotube-polymer complex is formed, and a dispersion in which such a complex is dispersed in water as a solvent can be obtained. The carbon nanotube-polymer complex may have a structure in which the polymer surrounds the surface of the carbon nanotube. Since the carbon nanotube-polymer complex has such a structure, the carbon nanotube-polymer complex has excellent dispersibility.

The carbon nanotubes may be used in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of water.

One of the characteristics of the present invention is that the cellulose-based polymer used is similar in weight to carbon nanotubes because only the weight of wrapping and dispersing carbon nanotubes is used, and specifically, cellulose-based polymer to carbon The weight ratio of the nanotubes is preferably 1: 1 to 1: 5.

In addition, after the step of preparing the dispersion, the dispersion may be coated on the substrate, followed by drying and peeling, to produce an electromagnetic wave shielding film containing the carbon nanotube-polymer complex.

As the substrate, a plastic substrate such as quartz, glass, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate, polystyrene, polypropylene, polyvinyl chloride (PVC)

After the substrate is washed with ethanol and then UV-irradiated to modify the surface, a certain amount of the dispersion is coated on the surface-modified substrate and dried in a vacuum oven to increase the attracting force of the molecules in the dispersion. A carbon nanotube-polymer composite thin film can be obtained.

As a method of applying the dispersion, dip coating, spray coating, spin coating, screen printing, spray coating, roll coating, blade coating, gravure coating or doctor blading can be used.

Hereinafter, the present invention will be described in detail with reference to examples and comparative examples. However, the scope of the present invention is not limited thereto.

≪ Examples 1 to 31 >

First, 100 g of distilled water was placed in a beaker at room temperature, and carboxymethyl cellulose (CMC, Carboxy Methyl Cellulose, average molecular weight: 350,000, Daejeon Gold) was added to the beaker according to the composition shown in Table 1, And then treated with a dispersing device for 30 minutes to prepare a first solution.

Next, a multi-wall carbon nanotube (MWCNT) (average diameter: 5 to 20 mu m, length: 1 to 10 mu m) was added to the first solution in accordance with the composition shown in Table 1 Then, a carbon nanotube-polymer dispersion was prepared by treating with a horn type ultrasonic dispersing apparatus equipped with a bubbling apparatus for 1 hour.

Next, the carbon nanotube-polymer dispersion prepared above was sprayed onto a UV-treated PVC substrate having a size of 10 mm x 10 mm to form a coating layer.

Next, the coating layer was dried in a vacuum oven at 40 DEG C for 3 hours, and then peeled from the substrate to produce an electromagnetic wave shielding film having a thickness of about 10 mu m.

<Comparative Example>

An electromagnetic wave shielding film was produced in the same manner as in Example 1, except that 0.6 g of polyaniline-based water-soluble polymer polyaniline butane sulfonate (PBS, average molecular weight 14,000, manufactured by Mitsubishi Chemical Corporation) was used as shown in Table 1.

&Lt; Evaluation on carbon nanotube-polymer dispersion >

The viscosity, dispersion stability, and film forming composition of the carbon nanotube-polymer dispersions of Examples and Comparative Examples were evaluated.

The &quot; viscosity &quot; (at 25 캜) was measured using a viscometer / rheometer-on-a-chip (VROC) method. That is, when a certain pressure is applied to each of the dispersions, the sensor attached to the chip detects the viscosity. Viscosity measurements were made 10 times and their mean values were derived.

&Quot; Dispersion stability &quot; was obtained by storing each of the prepared dispersions in an enclosed space and visually observing whether precipitation or phase separation occurred after 6 months. Specifically, it was judged that the case where the precipitation or the phase separation did not occur at all was evaluated as "excellent", the case where the precipitation or the phase separation was insignificant was judged as "normal", and the case where the precipitation or phase separation occurred was judged as "insufficient".

&Quot; Film Fabrication &quot; determined whether the dispersion could be coated on a substrate and dried to separate the coating layer from the substrate to obtain the shape of the film. Specifically, the case where the surface is smooth and the shape of the film is maintained is referred to as &quot; excellent &quot;, the case where the surface of the film is in the form of lumps or pores is somewhat retained, And it was judged that the case in which it was difficult to maintain the film form was "insufficient". The dispersion stability and the film manufacturability may not always coincide with each other. The dispersion stability is measured after 6 months, and the film manufacturability has no such time lapse.

Typically, the dispersion of Example 14 was observed with a scanning electron microscope (TEM), and the microstructure of the carbon nanotube-polymer composite was observed and shown in FIG. 6, it can be confirmed that an amorphous coating layer (CMC polymer layer) is formed on the surface of a carbon nanotube (MWCNT) having a crystal structure and the carbon nanotube is wrapped around the CMC polymer layer . As described in the following evaluation results, it is confirmed that the film has such structural characteristics that it is excellent in dispersion stability, film forming property, electromagnetic wave shielding property and restoring force.

<Evaluation of characteristics of electromagnetic wave shielding film>

Typically, an external view of the electromagnetic wave shielding film produced according to Example 14 is shown in Fig. 5, and a cross-sectional view thereof is shown in Fig. Referring to FIG. 6, it can be seen that an electromagnetic wave shielding film thinner than 10 μm can be manufactured.

The "surface resistance" was measured using a 4-point probe (SR1000N). After contacting the film with 4 probes, the test unit was fixed at Ω / sq and measured 10 times.

The electromagnetic wave shielding efficiency (EMI) was measured in the frequency range of 0.0 to 1.5 GHz. Examples were measurements of films peeled from the substrate, and Comparative Examples were measured by coating the dispersion on a PEN film and drying.

When the prepared electromagnetic wave shielding film is dispersed in distilled water, it has a "restoring force" which is returned to the carbon nanotube-polymer dispersion. Such restoring force is obtained by cutting a part of each film into distilled water and ultrasonic dispersion in a bath type for 30 minutes , And visually observing whether precipitation occurred. Resilience evaluation was carried out according to the same criteria as dispersion stability.

When the film could not be produced because it could not be separated from the substrate and the film could not be produced, the surface resistance and the electromagnetic wave shielding efficiency were not evaluated, but a part of the coating layer was collected to evaluate the restoring force.

The surface resistance, the electromagnetic wave shielding efficiency, and the restoring force evaluation results are shown in Table 1. In particular, the electromagnetic wave shielding efficiency for the films of Examples 10, 11, and 14 is shown in FIG. In the case of the comparative example, the coating layer was not separated from the substrate and the electromagnetic wave shielding efficiency was measured in a state of not being separated. Referring to FIG. 7, it can be seen that the electromagnetic wave shielding efficiency of the embodiment is superior to that of the comparative example.

Furtherance Dispersion property Characteristics of film CMC
(g) PBS
(g) CNT
(g) Viscosity
(cp) Dispersion
stability film
Manufacturing Sheet resistance
(Ω / sq) Shielding Efficiency
(dB) dynamic stability Example 1 0.05 0 0.1 0.9 X X - - X Example 2 0.05 0 3 1.0 X X - - X Example 3 0.05 0 6 1.0 X X - - X Example 4 0.1 0 0.05 1.3 △ X - - X Example 5 0.1 0 0.1 1.3 X ○ 829.6 21 ○ Example 6 0.1 0 One 1.6 △ △ 963.2 22 △ Example 7 0.1 0 3 1.6 △ △ 854.6 22 △ Example 8 0.1 0 5 1.6 △ △ 1.23K 21 △ Example 9 0.1 0 6 1.7 X X - - X Example 10 0.6 0 One 6.6 ○ ○ 4.8 32 ○ Example 11 0.8 0 One 7.8 ○ ○ 4.5 28 ○ Example 12 One 0 0.05 7.0 X X - - X Example 13 One 0 0.1 7.9 △ △ 2.5k 20 △ Example 14 One 0 One 8.4 ○ ○ 4.1 24 ○ Example 15 One 0 3 8.5 ○ ○ 3.9 22 ○ Example 16 One 0 5 9.0 ○ ○ 3.05 21 ○ Example 17 One 0 6 9.5 X X - - X Example 18 3 0 0.05 10.0 X X - - X Example 19 3 0 0.1 10.1 △ △ 2.39k 8 △ Example 20 3 0 One 10.2 △ △ 7.3 19 △ Example 21 3 0 3 10.5 ○ ○ 4.6 23 ○ Example 22 3 0 5 10.6 ○ ○ 4.0 22 ○ Example 23 3 0 6 10.7 △ △ 3.9 21 X Example 24 5 0 0.05 11.0 X X - - X Example 25 5 0 0.1 11.8 △ △ 586.7 19 △ Example 26 5 0 One 11.8 △ △ 5.8 22 △ Example 27 5 0 3 11.9 △ △ 3.6 22 △ Example 28 5 0 5 12.0 ○ ○ 2.9 21 ○ Example 29 5 0 6 12.1 △ △ 3.0 20 X Example 30 6 0 0.1 12.1 X X - - X Example 31 6 0 3 12.2 △ X - - X Comparative Example - 0.6 One 1.3 △ X 11.9 16 X

X: insufficient,?: Normal,?: Excellent

Referring to Examples 10, 11 and 14 in Table 1, as the amount of CMC was increased, the viscosity of the dispersion was increased and the electromagnetic wave shielding film could be stably produced. However, in the case of the comparative example using PBS as the polymer, the viscosity of the dispersion was very low even when the amount of PBS was the same as that of CMC, and the coating layer was not separated from the substrate, so that the electromagnetic wave shielding film could not be produced. From these results, it was found that when CMC and PBS were used as polymer, phase separation did not occur and carbon nanotubes could be stably dispersed. However, unlike PBS, when CMC was used, It is possible to separate the coating layer from the electromagnetic wave shielding film.

Especially, when CMC and CNT were 0.1 ~ 5g compared to 100g of water, the dispersion and electromagnetic shielding film showed better characteristics, especially CMC to CNT weight ratio of 1: 1 to 1: 5, respectively. Can be confirmed.

The terms used in the present invention are intended to illustrate specific embodiments and are not intended to limit the present invention. The singular presentation should be understood to include plural meanings, unless the context clearly indicates otherwise. The word &quot; comprises &quot; or &quot; having &quot; means that there is a feature, a number, a step, an operation, an element, or a combination thereof described in the specification. The present invention is not limited by the above-described embodiments and the accompanying drawings, but is intended to be limited only by the appended claims. It will be apparent to those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. something to do.

1: micro bubble generator 2, 3: ultrasonic horn
4: Polymer and carbon nanotube inlet 5: Pure water and additive inlet
6: Dispersion tank body 7: Dispersion bath cover
8: Dispersion tank 9: Dispersion
10: medium (constant temperature bath) 11: constant temperature bath
12: Media inlet 13: Dispersion outlet
14: Media outlet

Claims (14)

delete delete delete delete delete delete Dissolving the cellulose-based polymer in water to prepare a polymer solution; And
Introducing carbon nanotubes into the polymer solution and ultrasonically dispersing the carbon nanotubes to prepare a dispersion containing the carbon nanotube-polymer complex,
The cellulosic polymer is used in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the water and 0.1 to 5 parts by weight of the carbon nanotube is used in an amount of 100 parts by weight of the water,
The weight ratio of the cellulose-based polymer to the carbon nanotubes is 1: 1 to 1: 5,
The ultrasonic dispersion is performed using a horn type ultrasonic dispersing apparatus equipped with a bubbling apparatus,
Wherein the ultrasonic dispersing device comprises:
A dispersion tank made of a body and a cover;
A micro bubble generator disposed at a central portion of the lid; And
A plurality of ultrasonic horns symmetrically arranged around the micro bubble generator;
Wherein the electromagnetic wave shielding film is made of a metal. The method of manufacturing an electromagnetic shielding film according to claim 7, further comprising a step of coating and drying the dispersion on a substrate after the step of providing the dispersion. [Claim 8] The method of claim 7, wherein the cellulose polymer is selected from the group consisting of Methyl Cellulose, Hydroxy Ethyl Cellulose, Hydroxypropyl Methyl Cellulose, Hydroxyethyl Methyl Cellulose, Wherein at least one selected from the group consisting of Cellulose, Methyl Ethyl Cellulose, Carboxy Methyl Cellulose and Hydroxypropyl Cellulose is used. Way. delete delete delete delete delete

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