KR101948809B1 - Method for producing electromagnetic wave absorption structure and electromagnetic wave absorption structure - Google Patents

Abstract

A method for producing a polymer complex structure having an electromagnetic wave absorbing characteristic according to an embodiment of the present invention comprises: preparing a polymer compound composition in which a polymer matrix, a self-aligned carbon nanotube and carbon black are mixed by extruding; melt-kneading a polymer compound composition with a foaming agent, a cross-linking agent, and a nucleating agent for foaming to produce a composition for foaming; and producing the polymer complex structure using chemical cross-linking foaming with the composition for foaming. According to an embodiment of the present invention, it is possible to produce a foam structure in which the self-aligned carbon nanotube and carbon black are uniformly dispersed by a more simplified method, and the resulting complex can exhibit improved electrical conductivity and a foaming property.

Description

TECHNICAL FIELD [0001] The present invention relates to an electromagnetic wave absorbing structure,

The present invention relates to a method for producing a polymer composite structure having electromagnetic wave absorption characteristics and a polymer composite structure produced by the method. More particularly, the present invention relates to a method for producing a polymer composite structure having carbon nanotubes and carbon black and having electromagnetic wave absorption characteristics, and a polymer composite structure produced by the method.

TECHNICAL FIELD [0001] The present invention relates to a composite structure having electromagnetic wave absorption characteristics and a method of manufacturing the same, and relates to a constitution for use in absorbing electromagnetic waves in a microwave band and a manufacturing method thereof.

Conventional methods of suppressing electromagnetic waves include grounding, filtering, shielding, and absorption.

Grounding is the most basic method to minimize unnecessary noise. It is a method to connect the lead of the electronic circuit to the ground to prevent signal quality degradation due to electromagnetic noise or malfunction of electronic equipment.

The filtering method is a method of minimizing the interference of the electromagnetic wave to the system by installing a filter in the middle of the conducting wire in order to suppress the occurrence of the electromagnetic wave disturbance while the noise is conducted together when the current is conducted along the conductor. That is, it is a method of selecting a specific frequency or a frequency band to be used, passing only the electromagnetic wave of the specific frequency or frequency band, and using a filter that eliminates electromagnetic waves of the other frequency band.

The shielding method protects devices or devices that are susceptible to unwanted electromagnetic waves, and shields electromagnetic waves from being blocked by a shielding material between an external electromagnetic wave generating source and a device to be protected.

Absorption absorbs incident electromagnetic waves using absorbing materials and converts them into heat energy so that no reflected waves are generated. Currently, it is mainly used for military purposes.

Among the electromagnetic wave suppression methods, electromagnetic wave shielding and absorption methods are available from the material side. The dual electromagnetic wave shielding system simply reflects or scatters electromagnetic waves, which increases the malfunction and noise of electronic equipment due to the reflected electromagnetic waves, thereby causing secondary damage. Particularly, in the case of radioactive noise, there is a possibility that there may be a gap in the blocking wall even if it is well shielded, and there is a possibility of interference caused by components reflected inside the system, especially unwanted electromagnetic waves generated from the internal oscillator, There is an increasing interest in an electromagnetic wave absorber that does not stay in place but absorbs electromagnetic waves. The radio wave absorber suppresses noise causing malfunction of the electronic device, suppresses cross-talk between the circuit blocks and dielectric coupling in the proximity substrate, improves the receiving sensitivity of the antenna, And to reduce the human body's effects.

The mechanism of the radio wave absorber on the side of the structure is largely a resonance type and an impedance gradient type.

The resonance type electromagnetic wave absorber adjusts the impedance so that the incident electromagnetic wave partially reflects from the surface of the electromagnetic wave absorbing material and the other enters into the electromagnetic wave absorbing material and is reflected from the metal surface of the system. Also, if the thickness of the electromagnetic wave absorbing material is designed to be equal to 1/4 wavelength of the incident electromagnetic wave, the phase of the electromagnetic wave reflected after traveling to the surface of the system is changed by 1/2 wavelength as compared with the electromagnetic wave reflected from the surface of the electromagnetic wave absorbing material . When electromagnetic waves having different 180-degree phase are encountered on the surface of the material, they cancel each other out and are extinguished as heat, thereby exhibiting the radio wave absorption ability. The resonance type electromagnetic wave absorbing material is disadvantageous in that it can absorb only a narrow band of electromagnetic waves centering on a target frequency instead of being thin.

Graded dielectric absorbers are designed so that the impedance value gradually decreases from the material surface to the inside, so that the surface impedance of the material is similar to the impedance of the air, which is 377 Ω, but it decreases gradually toward the inside and there is no clear interface The incident electromagnetic wave is not reflected but gradually absorbed and extinguished while traveling inside the material. The impedance-gradient type electromagnetic wave absorbing material exhibits excellent electromagnetic wave absorption ability over a wide frequency band, but has a disadvantage that its thickness becomes thick. In the case of an impedance gradient structure, various types of configurations are possible, especially from a structural point of view. Generally, there are multi-layer type, flat type, and pyramidal type radio wave absorber structures.

As a method of manufacturing such a structure, a method of coating carbon black on a foam of an open cell or a close cell type is applied, but there is a problem that the open cell foam has a deterioration in mechanical properties and a coating uniformity failure. cell foams have a technical difficulty in the migration of the carbon black layer and the inclined properties in accordance with the increase of the coating thickness.

Korean Patent Registration No. 10-0358500 (registered on October 14, 2002)

The object of the present invention is to provide a method for producing a polymer composite in which carbon nanotubes and carbon black are uniformly dispersed in a self-aligned manner by a simpler method.

Another object of the present invention is to provide a method for producing a composite structure having improved electromagnetic wave absorbing properties that can improve mechanical properties and achieve uniform conductivity and inhibit migration of carbon materials in the surface layer .

It should be understood, however, that the present invention is not limited to the above-described embodiments, but includes the objects which can be clearly understood by those skilled in the art from the following description. can do.

According to an embodiment of the present invention, there is provided a method of manufacturing a polymer composite structure having electromagnetic wave absorption characteristics, comprising: preparing a polymer compound composition containing a polymer matrix, self-aligned carbon nanotubes and carbon black by extrusion processing; Melting and kneading the polymer compound composition with a foaming agent, a crosslinking agent, and a nucleating agent for foaming to prepare a foaming composition; And preparing a polymer composite structure using chemical crosslinking foaming with the foamable composition.

Also, the polymer matrix may be mixed with 10 to 50 parts by weight of the resin for flow control agent based on 100 parts by weight of the polyolefin resin.

Also, the polymer compound composition may include 0.1 to 0.5 parts by weight of self-aligned carbon nanotubes and 5 to 20 parts by weight of carbon black, based on 100 parts by weight of the polymer matrix.

The foamable composition may contain 5 to 20 parts by weight of a foaming agent, 1 to 5 parts by weight of a crosslinking agent, and 1 to 10 parts by weight of a nucleating agent for foaming, based on 100 parts by weight of the polymer compound composition.

In addition, the self-aligned carbon nanotube may include a plurality of carbon nanotubes having a diameter of 5 to 20 nm and a length of 1 to 600 um.

The polymer matrix may be a mixture of at least one selected from the group consisting of LDPE, LLDPE, HDPE and PP, the group consisting of PS, ABS and PU and the engineering plastics group of PET, PA, PBT and PPO and a mixture of low molecular weight LDPE, LLDPE, EVA, PMMA, PVA resin, and the like.

The foaming agent is selected from the group consisting of azodicarbonamide, azobisisobutylnitrile, barium azodicarboxylate, diazoaminobenzene. Nitroureadinitrosobentaemepentetramine, benzenesulfonylhydrazide, and the like. [0043] The term "

The foaming agent may be contained in an amount of 1 to 40 parts by weight based on 100 parts by weight of the polymer matrix.

In addition, the crosslinking agent may include a mixture of at least one selected from the group consisting of hydroperoxides, dialkyl peroxides, diacyl peroxides, peloxy esters, and ketone peloxides, which are organic peroxides.

The crosslinking agent may be included in an amount of 1 to 10 parts by weight based on 100 parts by weight of the polymer matrix.

The nucleating agent for foaming may include a mixture of at least one selected from the group consisting of sodium hydrogencarbonate, calcium carbonate, and zinc oxide.

The foaming nucleating agent may be included in an amount of 1 to 10 parts by weight based on 100 parts by weight of the polymer matrix.

According to another embodiment of the present invention, there is provided a polymer composite structure having an electromagnetic wave absorption property, comprising: preparing a polymer compound composition containing a polymer matrix, self-aligned carbon nanotubes and carbon black by extrusion processing; Melting and kneading the polymer compound composition with a foaming agent, a crosslinking agent, and a nucleating agent for foaming to prepare a foaming composition; And a process for producing a polymer composite structure using chemical crosslinking foaming with the foamable composition.

According to the embodiment of the present invention, it is possible to manufacture a composite having electromagnetic wave absorption characteristics in which carbon nanotubes and carbon black are self-aligned evenly dispersed in a more simplified manner, and the resulting composite has improved electrical conductivity and mechanical properties Lt; / RTI >

In addition, the structure having the electromagnetic wave absorption characteristics according to the embodiment of the present invention may have increased tensile strength, flexural strength, and impact resistance as compared to the structure of the open cell type.

In addition, the structure having the electromagnetic wave absorption characteristics according to the embodiment of the present invention can have improved surface migration characteristics and resistance uniformity of the inner / outer layers compared to the structure of the close cell type.

The effects obtainable in the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the description below will be.

1 is a flowchart of a method of manufacturing a polymer composite structure having electromagnetic wave absorption characteristics according to an embodiment of the present invention.
2A is an enlarged photograph of a self-aligned carbon nanotube using a scanning electron microscope (SEM).
FIG. 2B is a photograph of an enlarged view of an entangled carbon nanotube using a scanning electron microscope (SEM).
FIG. 3A is a photograph of a surface of a composite having electromagnetic wave absorption characteristics according to an embodiment of the present invention, magnified using a scanning electron microscope (SEM).
FIG. 3B is a photograph of the surface of the composite according to the comparative example magnified using a scanning electron microscope (SEM).
Figure 4 is a photograph of a foam-like composite made according to one embodiment of the present invention.
Figure 5 is a plot showing the measured permittivity and tangent loss of a foam-like composite made according to one embodiment of the present invention.
6 is a view showing electromagnetic wave absorptance data of a microwave band for each thickness of the foam-like composite manufactured according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. It should be understood, however, that the invention is not limited to the disclosed embodiments, but may be embodied in various forms and should not be construed as limited to the embodiments set forth herein, To fully disclose the scope of the invention to a person skilled in the art, and the scope of the invention is only defined by the claims.

In describing embodiments of the present invention, a detailed description of well-known functions or constructions will be omitted unless otherwise described in order to describe embodiments of the present invention. The following terms are defined in consideration of the functions in the embodiments of the present invention, which may vary depending on the intention of the user, the intention or the custom of the operator. Therefore, the definition should be based on the contents throughout this specification.

And, the singular forms used herein include plural forms unless the phrases expressly have the opposite meaning. Also, as used herein, the term " comprises " embodies certain features, areas, integers, steps, operations, elements and / or components, It does not exclude the existence or addition of a group.

1 is a flowchart of a method of manufacturing a polymer composite structure having electromagnetic wave absorption characteristics according to an embodiment of the present invention. A method of fabricating a polymer composite structure having electromagnetic wave absorption characteristics according to an embodiment of the present invention includes a polymer matrix, a self-aligned carbon nanotube (CNT), and a polymer compound Preparing a composition by extrusion processing (S110); (S120) a step of melt-kneading the polymer compound composition with a blowing agent, a cross-linking agent, and a nucleating agent to prepare a composition for foaming (S120); And a step (S130) of preparing a polymer composite structure by chemical crosslinking foaming the composition for foaming.

Hereinafter, a method for producing a polymer composite structure having electromagnetic wave absorption characteristics according to an embodiment of the present invention will be described in detail.

First, a method of manufacturing a composite according to an embodiment may include preparing a polymer compound composition in which a polymer matrix, a self-aligned carbon nanotube (CNT), and carbon black are mixed.

The polymer compound composition may include a self-aligned carbon nanotube, a conductive material composed of carbon black, and two or more polymer resins to form a polymer matrix. The two or more polymer resins to form the polymer matrix may be a polyolefin resin and a resin added for improving fluidity.

The polyolefin resin contained in the polymer matrix is not limited as long as it has excellent flowability and good mechanical properties. However, the polyolefin resin is not limited to LDPE (Low Density Polyethylene), LLDPE (Linear Low Density Polyethylene), HDPE High Density Polyethylene) and PP (Polypropylene), PS (Polystyrene), ABS (Acrylonitrile Butadiene Styrene) and PU (Polyurethane) and PET (Polyethylene Terephthalate), PA (Polyamide, Nylon), PBT (Polybutylene Terephthalate ), Polyphenylene oxide (PPO), and the like.

In order to improve the fluidity, the resin added is in order to compensate the disadvantage that the olefin resin as the main component of the polymer matrix, the self-aligned carbon nanotubes and the carbon black have poor compatibility with each other, The resin for improving fluidity may be a mixture of at least one selected from the group consisting of low molecular weight LDPE, LLDPE, ethylene vinyl acetate (EVA), polymethylmethacrylate (PMMA), and PVA (polyvinyl alcohol) resin. At this time, the fluidity controlling polymer resin may be contained in an amount of 10 to 50 parts by weight, or 30 to 40 parts by weight, based on 100 parts by weight of the polyolefin resin of the polymer matrix.

2A is an enlarged photograph of a self-aligned carbon nanotube using a scanning electron microscope (SEM). FIG. 2B is a photograph of an entangled carbon nanotube using a scanning electron microscope This is a photograph of a magnified observation.

The carbon nanotubes self-aligned as shown in FIG. 2A, unlike conventional carbon nanotubes having the tangled structure shown in FIG. 2B, have a plurality of carbons having a diameter of several to several tens nanometers and a length of several to several hundreds of micrometers Nanotubes are arranged in a bundle shape. Accordingly, when self-aligned carbon nanotubes are mixed with a polymer matrix, a plurality of bundles of carbon nanobots can be dispersed in a polymer matrix in a loosened form. However, the conventional carbon nanotubes having a tangled structure have poor dispersibility due to a strong van der Waals force between the carbon nanotubes, resulting in agglomerates, decreased electrical conductivity, and a decrease in mechanical properties due to a crack point do. On the other hand, self-aligned carbon nanotubes exhibit excellent dispersibility, enabling the provision of composites having more uniform and improved electrical, mechanical, and thermal properties.

The self-aligned carbon nanotube may be a conventional one having a plurality of carbon nanotubes arranged in a bundle shape, and may be a single walled carbon nanotube, a multi walled carbon nanotube, nanotube) and the like are not particularly limited. However, according to one embodiment, the self-aligned carbon nanotubes include a plurality of carbon nanotubes having a diameter of 5 to 20 nm and a length of 1 to 600 um. .

Meanwhile, according to one embodiment, the composition of carbon nanotubes and carbon black self-aligned with the polymer matrix can be prepared by a method of extrusion processing in a twin-screw extruder. That is, the self-aligned carbon nanotubes themselves are excellent in dispersibility, and even if a separate pretreatment or multistage physical dispersion method is not applied to the carbon nanotubes, the carbon nanotubes and the carbon black are uniformly dispersed in the polymer matrix A composition can be obtained.

At this time, the self-aligned carbon nanotubes may be contained in an amount of 0.1 to 2 parts by weight, or 0.1 to 1 part by weight, or 0.1 to 0.5 parts by weight, based on 100 parts by weight of the polymer matrix. However, when the carbon nanotubes are added in an excess amount, the dispersibility of the carbon nanotubes and the mechanical properties of the composite may be deteriorated. Accordingly, it is advantageous that the self-aligned carbon nanotubes are contained in an amount of 0.5 parts by weight or less based on 100 parts by weight of the polymer matrix.

The carbon black may be contained in an amount of 1 to 20 parts by weight, or 5 to 15 parts by weight based on 100 parts by weight of the polymer matrix. However, when the carbon black is added in an excessive amount, the dispersibility and the foaming property are lowered, and when the carbon black is added in a small amount, the conductivity can be reduced.

Meanwhile, a method of manufacturing a composite having electromagnetic wave absorption characteristics according to an exemplary embodiment may include mixing a polymer compound composition with a foaming agent, a crosslinking agent, and a nucleating agent for foaming, followed by melt-kneading using a 2-roll mill.

 According to one embodiment, the blowing agent is selected from the group consisting of azodicarbonamide, azobisisobutylnitrile, barium azodicarboxylate, diazoaminobenzene. Nitrourea dinitrophenol, nitroureadinitroso botentamepentetramine, and benzenesulfonyl hydrazide. In this case, the blowing agent may be contained in an amount of 1 to 40 parts by weight, or 5 to 20 parts by weight, based on 100 parts by weight of the polymer matrix.

Further, according to one embodiment, the cross-linking agent may be a mixture of at least one selected from the group consisting of hydroperoxides, dialkyl peroxides, diacyl peroxides, peloxy esters, and ketone peloxides which are organic peroxides. In this case, the crosslinking agent may be contained in an amount of 1 to 10 parts by weight, or 1 to 5 parts by weight, based on 100 parts by weight of the polymer matrix.

According to one embodiment, the nucleating agent for foaming may be a mixture of at least one selected from the group consisting of sodium hydrogencarbonate, calcium carbonate, and zinc oxide. At this time, the nucleating agent for foaming may be contained in 1 to 5 parts by weight, or 1 to 10 parts by weight, based on 100 parts by weight of the polymer matrix.

Best Mode for Carrying Out the Invention Hereinafter, preferred embodiments are described to facilitate understanding of the present invention.

However, the following examples are intended to illustrate the present invention without limiting it thereto.

Example  One

0.1 part by weight of self-aligned carbon nanotubes and 10 parts by weight of carbon black were mixed in 100 parts by weight of LDPE, and extrusion processing was carried out in a twin-screw extruder. The extrusion processing conditions were 2 passes at 200 ° C at a screw speed of 200 rpm and a feed rate of 18.

Example  1-1

3 parts by weight of the nucleating agent ZnO, 10 parts by weight of the nucleating agent calcium carbonate, 44 parts by weight of the blowing agent JTR-TL and 1.5 parts by weight of the crosslinking agent DCP were mixed with 100 parts by weight of the polymer compound extruded in Example 1, After the kneading, chemical crosslinking foaming was carried out using the foamable composition prepared. Chemical crosslinking foaming conditions were carried out at a temperature of 170 ° C for 23 minutes.

Example  1-2

3 parts by weight of the nucleating agent ZnO, 5 parts by weight of the nucleating agent calcium carbonate, 44 parts by weight of the blowing agent JTR-TL and 1.5 parts by weight of the crosslinking agent DCP were mixed with 100 parts by weight of the polymer compound extruded in Example 1, After the kneading, chemical crosslinking foaming was carried out using the foamable composition prepared. Chemical crosslinking foaming conditions were carried out at a temperature of 170 ° C for 23 minutes.

Example  2

100 parts by weight of a polymer resin mixed with LDPE 70% and EVA 30%, 0.1 part by weight of self-aligned carbon nanotubes and 10 parts by weight of carbon black were mixed and extruded in a twin-screw extruder. The extrusion processing conditions were 2 passes at 200 ° C at a screw speed of 200 rpm and a feed rate of 18.

Example  2-1

3 parts by weight of the nucleating agent ZnO, 10 parts by weight of the nucleating agent calcium carbonate, 44 parts by weight of the blowing agent JTR-TL and 1.5 parts by weight of the crosslinking agent DCP were mixed with 100 parts by weight of the extruded polymer compound in Example 2, After the kneading, chemical crosslinking foaming was carried out using the foamable composition prepared. Chemical crosslinking foaming conditions were carried out at a temperature of 170 ° C for 23 minutes.

Example  2-2

3 parts by weight of the nucleating agent ZnO, 5 parts by weight of the nucleating agent calcium carbonate, 44 parts by weight of the blowing agent JTR-TL and 1.5 parts by weight of the crosslinking agent DCP were mixed with 100 parts by weight of the extruded polymer compound in Example 2, After the kneading, chemical crosslinking foaming was carried out using the foamable composition prepared. Chemical crosslinking foaming conditions were carried out at a temperature of 170 ° C for 23 minutes.

Example  3

100 parts by weight of a polymer resin mixed with LDPE 50% and EVA 50%, 0.1 part by weight of self-aligned carbon nanotubes and 10 parts by weight of carbon black were mixed and extruded in a twin-screw extruder. The extrusion processing conditions were 2 passes at 200 ° C at a screw speed of 200 rpm and a feed rate of 18.

Example  3-1

3 parts by weight of the nucleating agent ZnO, 10 parts by weight of the nucleating agent calcium carbonate, 44 parts by weight of the blowing agent JTR-TL and 1.5 parts by weight of the crosslinking agent DCP were mixed with 100 parts by weight of the extruded polymer compound in Example 3, After the kneading, chemical crosslinking foaming was carried out using the foamable composition prepared. Chemical crosslinking foaming conditions were carried out at a temperature of 170 ° C for 23 minutes.

Example  3-2

3 parts by weight of the nucleating agent ZnO, 5 parts by weight of the nucleating agent calcium carbonate, 44 parts by weight of the blowing agent JTR-TL and 1.5 parts by weight of the crosslinking agent DCP were mixed with 100 parts by weight of the polymer compound extruded in Example 3, After the kneading, chemical crosslinking foaming was carried out using the foamable composition prepared. Chemical crosslinking foaming conditions were carried out at a temperature of 170 ° C for 23 minutes.

Example  4

100 parts by weight of a polymer resin mixed with LDPE 30% and EVA 70%, 0.1 part by weight of self-aligned carbon nanotubes and 10 parts by weight of carbon black were mixed and extruded in a twin-screw extruder. The extrusion processing conditions were 2 passes at 200 ° C at a screw speed of 200 rpm and a feed rate of 18.

Example  4-1

3 parts by weight of the nucleating agent ZnO, 10 parts by weight of the nucleating agent calcium carbonate, 44 parts by weight of the blowing agent JTR-TL and 1.5 parts by weight of the crosslinking agent DCP were mixed with 100 parts by weight of the extruded polymer compound in Example 4, After the kneading, chemical crosslinking foaming was carried out using the foamable composition prepared. Chemical crosslinking foaming conditions were carried out at a temperature of 170 ° C for 23 minutes.

Example  4-2

3 parts by weight of the nucleating agent ZnO, 5 parts by weight of the nucleating agent calcium carbonate, 44 parts by weight of the blowing agent JTR-TL and 1.5 parts by weight of the crosslinking agent DCP were mixed with 100 parts by weight of the extruded polymer compound in Example 4, After the kneading, chemical crosslinking foaming was carried out using the foamable composition prepared. Chemical crosslinking foaming conditions were carried out at a temperature of 170 ° C for 23 minutes.

Example  5

0.1 part by weight of self-aligned carbon nanotubes and 10 parts by weight of carbon black were mixed in 100 parts by weight of EVA, and extrusion processing was carried out in a twin-screw extruder. The extrusion processing conditions were 2 passes at 200 ° C at a screw speed of 200 rpm and a feed rate of 18.

3 parts by weight of a nucleating agent ZnO, 5 parts by weight of a nucleating agent calcium carbonate, 44 parts by weight of a blowing agent JTR-TL and 1.5 parts by weight of a crosslinking agent DCP were mixed and kneaded using a 2-roll mill in an amount of 100 parts by weight, The chemical crosslinking foaming was carried out using the composition for foaming. Chemical crosslinking foaming conditions were carried out at a temperature of 170 ° C for 23 minutes.

Comparative Example  One

0.1 part by weight of an entangled carbon nanotube and 10 parts by weight of carbon black were mixed with 100 parts by weight of a polymer resin mixed at a ratio of 70% of LDPE and 30% of EVA, followed by extrusion processing in a twin screw extruder. The extrusion processing conditions were 2 passes at 200 ° C at a screw speed of 200 rpm and a feed rate of 18.

3 parts by weight of a nucleating agent ZnO, 5 parts by weight of a nucleating agent calcium carbonate, 44 parts by weight of a blowing agent JTR-TL and 1.5 parts by weight of a crosslinking agent DCP were mixed and kneaded using a 2-roll mill in an amount of 100 parts by weight, The chemical crosslinking foaming was carried out using the composition for foaming. Chemical crosslinking foaming conditions were carried out at a temperature of 170 ° C for 23 minutes.

Table 1 below is a polymer matrix composition table, and Table 2 is a foam structural composition and physical property evaluation table.

Test Example  1 (observation of dispersion state of carbon nanotubes)

The surface of each composite obtained in Example 2 and Comparative Example was observed using a scanning electron microscope (SEM). The results are shown in FIGS. 3A and 3B. As shown in FIG. 3A, it was confirmed that the carbon nanotubes were evenly dispersed in the composite according to Example 2. FIG. On the other hand, as shown in FIG. 3B, it was confirmed that the carbon nanotubes were not uniformly dispersed in the composite according to the comparative example. In Fig. 3B, the dotted circle is aggregated carbon nanotubes.

Test Example  2 (Observation of surface resistance and foaming)

For each of the composites obtained in Examples and Comparative Examples, the respective foaming compositions and the surface resistance and the foaming state of the structure produced after the foaming process were observed, and the results are shown in Table 2 below. The surface resistance was measured using a Lorester surface resistance meter of Mitsubishi Chemical Co., Ltd. The foaming characteristics were visually observed on the surface state and the presence of the inner layer vacancy.

Polymer matrix composition Polymer matrix composition LDPE (rate) EVA (rate) CNT (phr) Carbon black (phr) Example 1 10 - 0.1 10 Example 2 7 3 0.1 10 Example 3 5 5 0.1 10 Example 4 3 7 0.1 10 Example 5 - 10 0.1 10 Comparative Example 1 7 3 0.1 10

Foam structure composition and physical property evaluation Foam composition Rs (Ω / □) firing
condition Comp'd
(g) ZnO
(phr) CaCO ₃
(phr) JTR-TL
(phr) DCP
(phr) surface Inner layer Example 1 1-1 400 3 10 44 1.5 > 13 > 13 ○ 1-2 400 3 5 44 1.5 > 13 > 13 ○ Example 2 2-1 400 3 10 44 1.5 4 5 △ 2-2 400 3 5 44 1.5 4 5 ○ Example 3 3-1 400 3 10 44 1.5 6.5 8.3 △ 3-2 400 3 5 44 1.5 6.1 8.4 △ Example 4 4-1 400 3 10 44 1.5 7.1 8.9 △ 4-2 400 3 5 44 1.5 7.5 6.9 △ Example 5 400 3 5 44 1.5 10 13 Х Comparative Example 1 400 3 5 44 1.5 8 10 ○

As can be seen from Table 2, it was found that the composition including the EVA as a flow modifier and the composition not containing EVA differ in the surface resistance. Also, it can be seen that the composition containing EVA of 50% or more tends to increase the surface resistance. The reason for this phenomenon is that the dispersion state of carbon nanotubes and carbon black is poor in a composition composed only of LDPE, and in a composition containing more than 50% EVA, EVA having good flowability is coated on surfaces of carbon nanotubes and carbon black, The contact resistance between carbon atoms increases. Furthermore, it has been confirmed that the composite of the embodiments prepared using the self-aligned carbon nanotubes has remarkably improved electrical characteristics as compared with the composite of the comparative example manufactured using the tangent carbon nanotubes.

FIG. 4 is a photograph of a foam-type composite prepared according to an embodiment of the present invention, and FIG. 5 is a graph showing a measured permittivity and a tangent loss of a foam-type composite produced according to an embodiment of the present invention And FIG. 6 is a view showing electromagnetic wave absorptance data of a microwave band for each thickness of a foam-like composite manufactured according to an embodiment of the present invention.

The above description is merely illustrative of the technical idea of the present invention, and various modifications and changes may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed herein are for the purpose of describing rather than limiting the technical spirit of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents thereof should be construed as falling within the scope of the present invention.

Claims (13)

Preparing a polymer compound composition containing a polymer matrix, self-aligned carbon nanotubes, and carbon black by extrusion processing;
Melting and kneading the polymer compound composition with a foaming agent, a crosslinking agent, and a nucleating agent for foaming to prepare a foaming composition; And
And a step of preparing a polymer composite structure by chemical crosslinking foaming with the foamable composition
A method for producing a polymer composite structure having electromagnetic wave absorption characteristics. The method according to claim 1,
Wherein the polymer matrix is obtained by mixing 10 to 50 parts by weight of a resin for flow control agent with respect to 100 parts by weight of a polyolefin resin
A method for producing a polymer composite structure having electromagnetic wave absorption characteristics. The method according to claim 1,
The polymer compound composition includes 0.1 to 0.5 parts by weight of self-aligned carbon nanotubes and 5 to 20 parts by weight of carbon black per 100 parts by weight of the polymer matrix
A method for producing a polymer composite structure having electromagnetic wave absorption characteristics. The method according to claim 1,
Wherein the foaming composition comprises 5 to 20 parts by weight of a foaming agent, 1 to 5 parts by weight of a crosslinking agent, and 1 to 10 parts by weight of a nucleating agent for foaming, based on 100 parts by weight of the polymer compound composition
A method for producing a polymer composite structure having electromagnetic wave absorption characteristics. The method according to claim 1,
Wherein the self-aligned carbon nanotube comprises a plurality of carbon nanotubes having a diameter of 5 to 20 nm and a length of 1 to 600 um
A method for producing a polymer composite structure having electromagnetic wave absorption characteristics. The method according to claim 1,
Wherein the polymer matrix comprises at least one selected from the group consisting of LDPE, LLDPE, HDPE and PP, the group consisting of PS, ABS and PU and the engineering plastics group of PET, PA, PBT and PPO and a mixture of low molecular weight LDPE, LLDPE, EVA, PMMA, and PVA resin, which is characterized in that it is made of a mixture of at least one selected from the group consisting of
A method for producing a polymer composite structure having electromagnetic wave absorption characteristics. The method according to claim 1,
The foaming agent is selected from the group consisting of azodicarbonamide, azobisisobutylnitrile, barium azodicarboxylate, diazoaminobenzene. And a mixture of at least one member selected from the group consisting of nitrourea dinitrilosobentamepentetramine and benzenesulfonylhydrazide.
A method for producing a polymer composite structure having electromagnetic wave absorption characteristics. 8. The method of claim 7,
Wherein the foaming agent is contained in an amount of 1 to 40 parts by weight based on 100 parts by weight of the polymer matrix
A method for producing a polymer composite structure having electromagnetic wave absorption characteristics. The method according to claim 1,
Wherein the cross-linking agent comprises a mixture of at least one selected from the group consisting of hydroperoxides, dialkyl peroxides, diacyl peroxide, peloxy esters, and ketone peloxide, which are organic peroxides
A method for producing a polymer composite structure having electromagnetic wave absorption characteristics. 10. The method of claim 9,
The crosslinking agent is contained in an amount of 1 to 10 parts by weight based on 100 parts by weight of the polymer matrix.
A method for producing a polymer composite structure having electromagnetic wave absorption characteristics. The method according to claim 1,
Wherein the foaming nucleating agent comprises a mixture of at least one selected from the group consisting of sodium hydrogencarbonate, calcium carbonate and zinc oxide
A method for producing a polymer composite structure having electromagnetic wave absorption characteristics. 12. The method of claim 11,
Wherein the foaming nucleating agent is contained in an amount of 1 to 10 parts by weight based on 100 parts by weight of the polymer matrix
A method for producing a polymer composite structure having electromagnetic wave absorption characteristics. A polymer composite structure produced by the method according to claim 1.

Images