KR101798835B1 - Electromagnetic wave shielding resin composition and molded article including the same - Google Patents

Abstract

The electromagnetic wave absorbing resin composition of the present invention comprises: a) 60 to 90% by weight of a polymer resin; b) 0.1 to 15% by weight of carbon nanotubes in the form of a rigid random coil having a static bending persistence of 100 nm to 500 nm; c) 0.1 to 20% by weight of the carbon compound excluding the carbon nanotubes; And a residual solvent, and has an electromagnetic wave reflection coefficient of -6 dB or less and a transmittance coefficient of electromagnetic wave of -10 dB or less at a frequency of 15 to 30 GHz.

Description

TECHNICAL FIELD [0001] The present invention relates to a resin composition for absorbing an electromagnetic wave and a molded article including the same. BACKGROUND ART [0002] Electromechanical wave absorbing resin composition,

The present invention relates to a resin composition for electromagnetic wave absorption and a molded article comprising the same.

As part of the advancement of automobiles and other vehicles, there is a growing demand for components with various designs and functionalities. Especially, as the problem of vehicle accidents is emerging, the technology of utilizing the transmission / reception control device such as the radar for the vehicle for increasing the safety of the driver in the automobile operation becomes important.

For example, ACC technology that controls the speed of the vehicle according to the speed of the forward vehicle by detecting the vehicle ahead, or CDM technology that operates the brake with the alarm when the vehicle collides with the preceding vehicle to be.

Also, in order to detect rear vehicle, radar cover and shield material are attached to radar module for effective use of such a transmission / reception control device for vehicle, and particularly, a radar which is widely used for a longer period, thereby protecting radar from ambient environment, moisture and electromagnetic noise .

Therefore, the radar shielding material used for the rearward radar should be a material having a capability of transmitting electromagnetic waves passing through a certain level or less, that is, a function of absorbing, while lowering the efficiency due to electromagnetic wave reflection.

When the reflection efficiency is increased, the absorption efficiency can be increased, but the absorber required by the radar shield material can not be used. In other words, in order to optimize the electromagnetic wave absorption function, it is possible to use the material as a radar shield material only when the effect of reflection is lowered and the permeation is minimized.

Generally, an electromagnetic wave absorbing material absorbs and shields incident electromagnetic wave energy by using conductive, dielectric and magnetic loss, and converts it into another energy, thereby effectively reducing the intensity of the electromagnetic wave.

In addition, the conventional electromagnetic wave absorber has a different filler depending on the frequency band or the absorption method. One of them is a magnetic particle filler generally used for designing the absorber and dispersed in a paint or a plastic composite material do. However, when a composite material is produced using a ferrite-based filler, the absorption effect may be enhanced, but the specific gravity is increased, the physical properties of the molded product are lowered, and the injection moldability is deteriorated.

The conventional electromagnetic wave absorber generally has an absorption function in the range of 100 MHz to 2.4 GHz, or rarely 5 or 10 GHz, which is an area where an electromagnetic wave absorber is required. Since a radar used in an automobile is applied in a higher microwave range, In order to develop an absorbing material capable of absorbing electromagnetic waves in the used region, material designing should take place in consideration of characteristics in the high frequency region.

Therefore, it is urgently required to develop a radar cover shield material for electromagnetic wave absorption, which has low electromagnetic wave reflection efficiency and transmission efficiency characteristic that can be applied to the automobile industry, so that electromagnetic wave is absorbed and does not hinder signal transmission of the radar.

Related technologies include KR0787562B1 and JP4897975B2.

An object of the present invention is to provide a resin composition for electromagnetic wave absorption which absorbs noise reflected from a vehicle body and a bumper when applied to a vehicle rear side radar shielding material to stabilize radar performance.

Another object of the present invention is to provide a resin composition for electromagnetic wave absorption that optimizes the performance of a vehicle radar through a reflection coefficient and transmission coefficient control in a very high frequency range.

It is still another object of the present invention to provide a molded article comprising the resin composition for electromagnetic wave absorption.

The above and other objects of the present invention can be achieved by the present invention described below.

One aspect of the present invention is a composition comprising: a) 60 to 90% by weight of a polymeric resin; b) 0.1 to 15% by weight of carbon nanotubes in the form of a rigid random coil having a static bending persistence of 100 nm to 500 nm; c) 0.1 to 20% by weight of the carbon compound excluding the carbon nanotubes; And a residual solvent, and has an electromagnetic wave reflection coefficient of -6 dB or less and a transmittance coefficient of -10 dB or less at a frequency of 15 to 30 GHz.

In an embodiment, the polymer resin is selected from the group consisting of polybutylene terephthalate resin, polyethylene terephthalate resin, aromatic polyamide resin, polyamide resin, polycarbonate resin, polystyrene resin, polyphenylene sulfide resin, polysulfone resin, , Polyetherimide resin, polyetheretherketone resin, polyarylate resin, polymethylmethacrylate resin, polypropylene resin, polyethylene resin, polyacrylonitrile butadiene styrene copolymer resin, polytetramethylene oxide-1,4 Butadiene copolymer resins, styrene-based resins, fluororesins, polyacrylonitrile resins, acrylic resins, polypyridine resins, polytriazole resins, polypyrrolidine resins, polybenzothiazole resins, polybenzimidazole resins, Furan resins, polyurea resins, polyphosphazenes Pond, may comprise a silicone-based resin, epoxy-based resins, phenol based resins, polyurethane-based resin, etc., and one or more mixtures thereof.

In embodiments, the carbon nanotubes may be single-walled, double-walled, thin multi-walled, multi-walled, multi-walled, Combinations thereof, and the like.

In an embodiment, the carbon compound other than the carbon nanotubes may include at least one selected from carbon black, graphene, fullerene, graphite, graphite oxide, carbon fiber, and mixtures thereof.

In an embodiment, the carbon nanotubes and the carbon compounds other than the carbon nanotubes may be contained in a weight ratio of 1: 0.1 to 1: 150.

In an embodiment, it may further include at least one selected from inorganic fillers, coupling agents, lubricants, and the like.

In embodiments, the surface resistance may be from 10 ⁶ to 10 ¹² (Ω / sq).

Another aspect of the present invention relates to a molded article produced by extruding, injection molding or thermoforming the electromagnetic wave absorbing resin composition.

In an embodiment, the molded article may be an electromagnetic wave absorbing material for a vehicle.

In a specific example, the electromagnetic wave absorber for a vehicle may be a shielding material for a cover of a radar transceiver.

INDUSTRIAL APPLICABILITY The resin composition for electromagnetic wave absorption and the molded article including the same according to the present invention can absorb noise reflected from the vehicle body and the bumper when applied to a vehicle rear side radar shielding material to stabilize the radar performance and control the reflection coefficient and transmission coefficient in an ultra- It is effective to optimize the radar performance of the vehicle.

1 is a conceptual view showing an absorption process in which an electromagnetic wave is transmitted through a radar shield material for a vehicle and is reflected.
2 is a conceptual diagram illustrating a process in which a transmission frequency is reflected, transmitted, and absorbed by a horn antenna.
3 is a graph showing reflection coefficients and transmission coefficients of carbon nanotubes and carbon compounds in the resin composition for electromagnetic wave absorption.
4 is a graph showing the measurement results of the reflection coefficient and the transmission coefficient according to Comparative Example 1. Fig.
5 is a graph showing the measurement results of the reflection coefficient and the transmission coefficient according to Comparative Example 2. Fig.
FIG. 6 is a graph showing the measurement results of the reflection coefficient and the transmission coefficient according to Comparative Example 3. FIG.
7 is a graph showing the measurement results of the reflection coefficient and the transmission coefficient according to Comparative Example 4. Fig.
8 is a graph showing the measurement results of the reflection coefficient and the transmission coefficient according to Example 1. Fig.
9 is a graph showing the measurement results of the reflection coefficient and the transmission coefficient according to the second embodiment.

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

Resin composition for electromagnetic wave absorption

One aspect of the present invention relates to a resin composition for absorbing electromagnetic waves. The resin composition for electromagnetic wave absorption comprises a polymer resin, a carbon nanotube in the form of a rigid random coil, a carbon compound excluding the carbon nanotubes, and a residual solvent, and has an electromagnetic wave reflection coefficient at a frequency of 15 to 30 GHz coefficient is -6dB or less and the electromagnetic wave transmission coefficient is -10dB or less.

1 is a conceptual view showing an absorption process in which an electromagnetic wave is transmitted through a radar shield material for a vehicle and is reflected.

1, a radar shield member 140, which is a transceiver for a vehicle formed according to an embodiment of the present invention, is included in a signal processing module 120 under a vehicle body 110 and is mounted on a vehicle body 110 or a bumper 130 It absorbs reflected noise (frequency) to stabilize the radar performance and optimize the performance of the vehicle radar by controlling the reflection coefficient and transmission coefficient in the very high frequency range.

2 is a cross-sectional view illustrating a process of transmitting, reflecting, transmitting, and absorbing a transmission frequency to a horn antenna.

Referring to FIG. 2, the horn antenna 200 is disposed at both horn portions of a radar for a vehicle. The horn antenna 200 absorbs, reflects, and transmits an electromagnetic wave (frequency) transmitted thereto using an absorber material 210 have. More specifically, when the transmission frequency S1 passes through the absorber 210, the frequency S21 to be absorbed becomes larger and the frequency S12 to be transmitted and the frequency S11 to be reflected can be reduced. At this time, electromagnetic waves transmitted to the workpiece may cause electromagnetic wave loss due to reflection and absorption by the radar shield material. Therefore, it is important to prevent the generation of noise due to the reflection of the electromagnetic wave and at the same time to lower the electromagnetic wave to be transmitted and to prevent the signal transmission of the radar for the vehicle from being hindered. In this connection, the electromagnetic wave reflection coefficient and the transmission coefficient have great significance.

3 is a graph showing the reflection coefficient (A) and the transmission coefficient (B) of carbon nanotubes and carbon compounds in the resin composition for electromagnetic wave absorption.

Referring to FIG. 3, the electromagnetic wave reflection coefficient A and the electromagnetic wave transmission coefficient B indicate the relationship between the carbon nanotube (a) and the content of the hetero-carbon compound (b) except for the carbon nanotubes (% By weight) ratio. More specifically, when the resin composition for electromagnetic wave absorption contains less carbon nanotube (a), the transmission coefficient is increased but the reflection coefficient is decreased. On the other hand, when the carbon nanotube (a) Can be lowered. In addition, when the resin composition for electromagnetic wave absorption contains a heterogeneous carbon compound (b) other than the carbon nanotubes, both the reflection coefficient and the transmission coefficient are both high, but there is a limit, I can not. Also, when the carbon nanotube (a) has a critical point or more, the reflection coefficient and the transmission coefficient of the carbon nanotube (a) increase sharply, but the reflection coefficient and the transmission coefficient may be opposite to each other. In addition, the carbon nanotube (a) can not be charged in a large amount due to bulky properties, and physical properties and moldability may be deteriorated as the amount of the carbon nanotube (a) is increased. That is, since the degree of absorption (efficiency) of the electromagnetic wave is influenced by the electrical conductivity (surface resistance), reflectivity and permeability of the absorber, the electrical conductivity, reflection coefficient and transmission coefficient of the resin composition can be very important factors for electromagnetic wave absorption And the present invention has been made in order to implement such a technical idea. Therefore, as described above, it is necessary to control the reflection coefficient and the absorption coefficient for the formation of the resin composition for electromagnetic wave absorption according to the present invention. Such adjustment is required for the carbon nanotube (a) and the hetero carbon compound except for the carbon nanotube (b). < / RTI >

The electromagnetic wave reflection coefficient may be -6dB or less, for example, -6.5dB or less. The resin composition for electromagnetic wave absorption according to the present invention has the effect of absorbing almost all the electromagnetic waves in the very high frequency range of 15 to 30 GHz.

The electromagnetic wave transmission coefficient may be -10 dB or less, for example, -10.5 dB or less. The resin composition for electromagnetic wave absorption according to the present invention has the effect of absorbing almost all the electromagnetic waves in the very high frequency range of 15 to 30 GHz.

In the present invention, the electromagnetic wave reflection coefficient and the transmission coefficient can be obtained in the frequency range of 15 to 30 GHz, for example, in the frequency range of 18 to 25 GHz. In the above frequency range, the electromagnetic wave absorbing resin composition formed by the present invention can be suitably used as a shield material for a radar cover which is a transceiver for a vehicle.

The resin composition for electromagnetic wave absorption may have a surface resistance of 10 ⁶ to 10 ¹² (Ω / sq), for example, 10 ⁶ to 10 ⁸ (Ω / sq). In the above range, it is possible to replace the antenna substrate using a conventional metal alloy substrate such as magnesium to maintain its electrical characteristics (surface resistance), thereby satisfying the electrical resistance requirements properly.

Hereinafter, components constituting the present invention will be described in detail.

(A) Polymer resin

The polymer resin may be included as a base polymer of the resin composition for electromagnetic wave absorption of the present invention and hybridized with carbon nanotubes and carbon compounds other than the carbon nanotubes to achieve optimal reflection coefficient and transmission coefficient efficiency.

The polymer resin is not particularly limited, and examples thereof include polybutylene terephthalate resin, polyethylene terephthalate resin, aromatic polyamide resin, polyamide resin, polycarbonate resin, polystyrene resin, polyphenylene sulfide resin, polysulfone resin , Polyether sulfone resin, polyether imide resin, polyether ether ketone resin, polyarylate resin, polymethyl methacrylate resin, polypropylene resin, polyethylene resin, polyacrylonitrile butadiene styrene copolymer resin, polytetramethylene Butadiene copolymer resin, styrene resin, fluorine resin, polyacrylonitrile resin, acrylic resin, polypyridine resin, polytriazole resin, polypyrrolidine resin, polybenzothiazole resin, polybenzimidazole resin Resin, polydibenzofuran resin, polyurea A resin, polyphosphazene resin, silicon resin, epoxy-based resins, phenol based resins, polyurethane-based resin, etc., and one or more mixture thereof may also include, alone or in combination. Preferably, the polymer resin may include a thermoplastic resin, and more preferably, it may include a polycarbonate resin, a polymethylmethacrylate resin, and the like.

The polymer resin may have a viscosity at 25 ° C of 500 to 5000 cps, for example, 1000 to 3000 cps. In the viscosity range, excellent workability is obtained when the resin composition for electromagnetic wave absorption of the present invention is formed, and excellent physical properties such as heat resistance, moisture resistance, and heat resistance are obtained.

The polymer resin may have a weight average molecular weight of 20,000 to 50,000 g / mol, for example, 30,000 to 40,000 g / mol. Within the above-mentioned range, the hybrid composition of the present invention has excellent hybrid reactivity and excellent physical properties such as heat resistance and chemical resistance.

The polymer resin may include 60 to 90% by weight, for example, 65 to 75% by weight, based on 100% by weight of the resin composition for electromagnetic wave absorption. When the content of the polymer resin is less than 60% by weight, the effect of absorbing electromagnetic waves is insignificant and the physical strength is lowered. When the content exceeds 90% by weight, the content of carbon nanotubes and carbon compounds, which are conductive materials to be added together, There is a problem that it is difficult to realize a sufficient physical property effect because the hybridization is not appropriate when the radar shield is remodeled.

(B) Carbon nanotubes

The carbon nanotubes in the form of the rigid random coil may be included for the purpose of enhancing physical properties such as workability, durability and impact resistance while performing a coating agent exhibiting electrical conductivity when the resin composition of the present invention is formed.

The carbon nanotubes of the rigid random coil type have an effective bending modulus greater than thermal energy (kT, where k is a Boltzmann constant and T is an absolute temperature) Can be defined as carbon nanotubes in which elastic deformation due to thermal energy does not occur within a length and the total size (distance between ends) of the particle is linearly proportional to the square root of the apparent molecular weight.

The carbon nanotubes in the form of rigid random coils may include carbon nanotubes in the form of rigid random coils disclosed in Korean Patent No. 10-2006-0107451 (published on Aug. 20, 2007) of the present applicant.

The static bending persistence means an average value of radius of curvature when the rigid random coil type carbon nanotubes have a continuous curvature and more precisely can be defined by the following Equation 1 using a statistical physics .

[Equation 1]

Where Lp is an arbitrary segment length, and θ is an angle from the axis. In this case, Db is the bending ratio, R is the end-to-end distance vector, lsp = Clp0 is the static zero velocity, C is the constant, L is the expanded length. In addition, the folding ratio may include a bending ratio disclosed in Korean Patent No. 10-2006-0107451 (published on Aug. 20, 2007), which the present applicant intends to write.

In the present invention, the static bending persistence may be 100 nm to 500 nm, for example, 100 nm to 350 nm. When the static permanent magnet length is less than 100 nm, it is difficult to maintain the rigid random coil type according to the present invention. When the static permanent magnet length is more than 500 nm, the absorption performance of the transmission frequency for electromagnetic wave absorption is deteriorated.

The rigid random coil type carbon nanotubes may be single-walled, double-walled, thin multi-walled, multi-walled, multi-walled, And the like.

The carbon nanotubes of the rigid random coil type may have a bending ratio (Db) of 0.1 to 0.8, for example, 0.2 to 0.6. It is possible to prevent a decrease in electrical conductivity due to an increase in defects in the bending ratio range and to solve the problem that it is difficult to form an isotropic material due to strong anisotropy.

The carbon nanotubes of the rigid random coil type may have a weight average molecular weight of 100,000 to 900,000,000 g / mol, for example, 10,000 to 900,000,000 g / mol. In the weight-average molecular weight range, hybridization for forming the resin composition of the present invention is suitable in terms of electrical conductivity and rigidity, and uniform dispersion of particles due to twisting of particles can be prevented.

The rigid random coil type carbon nanotubes may be contained in a ratio of 1: 0.1 to 1: 150, for example, in a ratio of 1: 0.1 to 1: 100 in terms of weight ratio (carbon nanotube: carbon compound) . In the above weight ratio range, optimal hybrid mixing is performed at the time of forming the resin composition of the present invention, and excellent electromagnetic wave absorption effect can be obtained by controlling the critical point of the reflection coefficient and the transmission coefficient.

The carbon nanotubes in the form of the rigid random coil may contain 0.1 to 15% by weight, for example, 0.1 to 10% by weight, based on 100% by weight of the resin composition for electromagnetic wave absorption. If the content is less than 0.1 wt%, the effect of addition is not exhibited, and the electrical conductivity is lowered and the electromagnetic wave absorption effect is insignificant. When the content exceeds 15 wt%, the dispersion is not uniformly distributed in the resin, Moisture resistance, and cold and cold properties, resulting in an increase in cost compared to efficiency.

(C) Carbon compound

The carbon compound may be included for the purpose of imparting electrical conductivity to a vehicular radar transceiver for absorbing electromagnetic waves through optimal hybrid bonding with the carbon nanotubes when forming the resin composition of the present invention.

The carbon compound may be at least one selected from the group consisting of carbon black, graphene, fullerene, graphite, graphite oxide, carbon fiber, and mixtures thereof, .

The carbon compound may have an average particle diameter of 0.0001 to 5000 nm, for example, 0.001 to 3500 nm. In the above range of particle diameter, when the carbon compound is hybridized with the polymer resin and the carbon nanotube, the dispersion is uniform and the electromagnetic wave absorbing effect is excellent.

The carbon compound may be contained at a weight ratio (carbon nanotube: carbon compound) of 1: 0.1 to 1: 150, for example, in a ratio of 1: 0.1 to 1: 100 to the carbon nanotubes. In the above weight ratio range, optimal hybrid mixing is performed at the time of forming the resin composition of the present invention, and excellent electromagnetic wave absorption effect can be obtained by controlling the critical point of the reflection coefficient and the transmission coefficient.

The carbon compound may include 0.1 to 20% by weight, for example, 0.1 to 15% by weight, based on 100% by weight of the resin composition for electromagnetic wave absorption. When the content is less than 0.1% by weight, the effect of addition is not exhibited and the electrical conductivity is poor and the electromagnetic wave absorbing effect is insignificant. When the content is more than 20% by weight, Moisture resistance, and cold and cold properties, resulting in an increase in cost compared to efficiency.

solvent

The solvent may be included for the purpose of improving smoothness, fluidity, and workability by adjusting the viscosity of the resin composition for electromagnetic wave absorption, facilitating the work of forming a molded article, and adjusting the volatilization rate of the solvent.

Examples of the solvent include aromatic hydrocarbon solvents such as toluene and xylene; Ester solvents such as ethyl acetate, n-butyl acetate and n-amyl acetate; Ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone; Alicyclic hydrocarbon solvents such as cyclohexane, methylcyclohexane and ethylcyclohexane; Petroleum hydrocarbon solvents such as mineral spirits; Ethylene glycol monomethyl ether acetate, ethylene glycol monomethyl ether acetate, ethylene glycol ethyl ether acetate, ethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether propionate, diethylene glycol ethyl ether acetate, diethylene glycol monobutyl ether acetate And ether-based solvents such as glycol ether esters and the like. These solvents may be used singly or in combination of two or more, and the kind thereof is not limited thereto.

The solvent may be contained in a residual amount other than the content of the polymer resin, the carbon nanotube, and the heterogeneous carbon compound. In addition, the solvent is not particularly limited, for example, the content of the solvent can be changed according to the kind of a desired molded article such as a radar for absorbing electromagnetic waves and the forming method. However, in one embodiment of the present invention, To 10% by weight, such as 10% by weight to 20% by weight. It is possible to prevent the problem of deterioration of the physical properties of the resin composition such that the smoothness and workability of the resin composition are appropriate in the above content range and that the lowering of the dilution solid content adversely affects the formation of molded products such as color unevenness, .

additive

The additive may be included for the purpose of performing hybridization between the polymer resin, the carbon nanotube and the carbon compound in forming the resin composition of the present invention more appropriately and realizing excellent physical properties such as heat resistance, moisture resistance, durability and chemical resistance.

In addition to the above-mentioned polymer resin, carbon nanotube, and carbon compound, the additive may further include at least one of inorganic filler, coupling agent, lubricant, and dispersant.

The inorganic filler may include at least one of glass fiber, talc, calcium carbonate, silica and the like, alone or in combination, in order to reinforce mechanical strength in the resin composition of the present invention. Since the polymer resin of the present invention has a high flexural modulus as a whole and may have a relatively low dimensional stability and mechanical strength, it is preferable to add an inorganic powder such as glass fiber, talc, calcium carbonate, silica, A stiffness reinforce effect can be implemented. That is, the inorganic powder particles may act as a nuclearizing agent that affects the crystal formation of the polymer resin, thereby enhancing the mechanical strength by causing an anchor effect. The inorganic filler may include 5 to 25 wt%, for example, 10 to 20 wt%, based on 100 wt% of the resin composition for electromagnetic wave absorption. If the inorganic filler is added in an amount of less than 5 wt%, the polymeric resin will not function as a nuclearizing agent that affects the crystal formation of the polymer resin, resulting in a decrease in mechanical strength. If the inorganic filler is added in an amount exceeding 25 wt% The content of the polymer resin impregnated with these fillers becomes very small because the compound is compounded together with the carbon nanotubes or the carbon compound, and the binding strength can not be sufficiently provided, so that the mechanical strength is adversely affected.

The coupling agent is used to improve the interfacial adhesion between the polymer resin used as the base polymer and the talc, calcium carbonate, glass fiber used as the inorganic reinforcing agent, carbon nanotubes as the conductive material, and carbon compounds, etc. Can be included. The coupling agent improves the compatibility with the heterogeneous inorganic additives to the polymer resin, so that a larger amount of the conductive material can be included, and mechanical properties such as elongation, flexural strength, impact strength, It can play a role of improving the strength. For example, when an acid anhydride such as maleic anhydride and an amine such as diethylamine (DEA) are added and a co-extruded coupling agent is used, Surface modification occurs between the polymer resin and these binders, and the effect of reinforcing the physical properties is exhibited. The coupling agent may include one or more of, for example, maleic anhydride, glycidylmethacrylate or oxazoline. The acid anhydride such as maleic anhydride reacts with an amine to form an imine compound in the ring opening state, and then dehydration reaction occurs to cause intermolecular bonding. The acid anhydride used as the coupling agent may contain 0.2 to 5% by weight, for example, 0.5 to 3% by weight based on 100% by weight of the resin composition for electromagnetic wave absorption. If the acid anhydride is added in an amount exceeding 5% by weight, it can be ignited by reaction with water generated during extrusion reaction. If the amount of the acid anhydride is less than 0.2% by weight, the intermolecular bonding reaction occurs very weakly. There is a problem that it is difficult to expect a reinforcement effect. Ethylene copolymers (EMA, EEA, EBA), which are polymerized with ethylene and acrylic acid and have self-polarity and compatibility with polymer resins, may be used as the non-reactive compatibilizer, or DuPont Fusabond M613-05 manufactured by Mitsubishi Heavy Industries, Ltd. may be used, but the kind thereof is not limited thereto as long as it implements the technical idea of the present invention.

In the lubricant (or dispersant), since a heterogeneous inorganic material is added to the polymer resin, a compatibility member is generated between the different compounds in the compounding operation, or the inorganic matter content is relatively larger than the resin amount, It can be included for smooth extrusion work. The lubricant (or dispersant) comprises a metal stearic acid such as low molecular weight waxes (PE wax, LC wax), zinc stearate, calcium stearate, magnesium stearate, . The lubricant (or dispersant) may include 1 to 3% by weight, for example, 1.5 to 2.5% by weight based on 100% by weight of the resin composition for electromagnetic wave absorption. If the amount of the lubricant (or dispersant) is more than 3% by weight, low-molecular-weight wax or metal stearic acid easily blooms and the wax component migrates to the surface of the structure to cause surface defects. When the wax component is transferred to the surface of the injection structure (intenna substrate), the electrical conductivity is lowered, which may result in the inverse function of weakening the energizing function. On the other hand, if less than 1% by weight of the lubricant (or dispersant) is used, it is difficult to expect a sufficient kneading effect, so that the dispersion or distribution of the inorganic filler added decreases.

The additive may be added in an amount of 0.1 to 30% by weight, for example, 1 to 20% by weight based on 100% by weight of the ultraviolet ray curable coating composition. When the resin composition for electromagnetic wave absorption is formed in the above range, hybrid bonds between the polymer resin and the carbon nanotubes and the carbon compound can be more appropriately performed, and physical properties such as smoothness and light resistance can be excellently realized.

Molded product

Another aspect of the present invention relates to a molded article produced by extruding, injection molding or thermoforming the resin composition for electromagnetic wave absorption.

The above-mentioned electromagnetic wave-absorbing resin composition of the present invention can be mixed and a molded article can be produced by a known method. Mixing of each of these components can be made into pellets by conventional extrusion processing, and the molded pellets can be manufactured into extruded molding, injection molding, thermoforming, and the like to be used as a sheet, film, panel, Can be used.

The molded product is a plastic molding that can be thermally conductive, electrostatically dispersed, or prevented from static electricity by controlling the electromagnetic wave absorbing effect, and has an advantage of being able to replace expensive heavy metal materials. The molded product may be, for example, an electronic control unit (electronic control unit) material for automobile lightening or an electromagnetic wave absorbing material for a vehicle, preferably an electromagnetic wave absorbing material for a vehicle.

The electromagnetic wave absorber for a vehicle may be a shield material for a cover of a radar transceiver. The radar transceiver may be implemented as a RAM shielding material in which a radome, an antenna module, an RF module, and a signal processing module are sequentially formed as a blind spot detector (BSD) of a vehicle such as an automobile. 1, a shield member 140 for a radar cover, which is a vehicle transceiver formed according to an embodiment of the present invention, is included in a signal processing module 120 on a vehicle body 110, And the radar performance is stabilized by absorbing the noise (frequency) reflected from the bumper 130, and the radar performance of the vehicle is optimized through adjustment of the reflection coefficient and the transmission coefficient in the very high frequency range.

Hereinafter, the configuration and operation of the present invention will be described in more detail with reference to preferred embodiments of the present invention. However, the following examples are provided to aid understanding of the present invention, and the scope of the present invention is not limited to the following examples. The contents not described here are sufficiently technically inferior to those skilled in the art, and a description thereof will be omitted.

Example

Example 1

(B) a carbon nanotube in the form of a rigid random coil having a static specific length of 110 nm and (B) a thermoplastic resin polycarbonate (Caliber 300-30, LG-DOW) C) Carbon black, which is a different kind of carbon compound except for the carbon nanotubes, was added. Then, melt-spinning and injection molding were carried out with a twin-screw extruder at 250 ° C. and 300 rpm to prepare a resin composition sample for electromagnetic wave absorption of 3 mm in thickness. Then, the reflection coefficient and the transmission coefficient were measured using the above specimen.

Example 2

A resin composition specimen for electromagnetic wave absorption was prepared in the same manner as in Example 1 except that the resin composition was prepared in the composition shown in the following Table 1, and then the reflection coefficient and the transmission coefficient were measured using the specimen.

Comparative Examples 1 to 4

A resin composition specimen for electromagnetic wave absorption was prepared in the same manner as in Example 1 except that the resin composition was prepared in the composition shown in the following Table 1, and then the reflection coefficient and the transmission coefficient were measured using the specimen.

Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 ingredient A (% by weight)   60 ~ 78 68 to 74 60 to 69 50 to 64 55 ~ 70 70 ~ 75 B Static persistence length (nm) 110 320 500 10 0 500 Content (% by weight) 2 to 5 1-2 15-20 1-5 0 10 to 15 C (% by weight) 5 to 10 10 to 15 1-5 20 ~ 30 15 to 30 0 Solvent (% by weight) 10 10 10 10 10 10 Additive (% by weight) 5 5 5 5 5 5 Total content (% by weight) 100 100 100 100 100 100 Properties Reflection Coefficient (dB) -6 -6.5 -3 -4 -3.5 -1.5 Transmission Factor (dB) -12 -10.5 -2 -2 Impossible Impossible

Measurement result

4 to 7 are graphs showing the measurement results of the reflection coefficient and the transmission coefficient according to Comparative Example 1-4.

Referring to FIGS. 4 to 7, the comparative example 1-4 is different from the example 1-3 according to the present invention in that the filler is not contained in the general plastic or the filler is not properly used. In this case, It is confirmed that the absorption efficiency is deteriorated and the waveform is uneven or out of the range.

8 to 9 are graphs showing the measurement results of the reflection coefficient and the transmission coefficient according to Example 1-2.

Referring to FIGS. 8 to 9, according to the present invention, a polymeric resin, a carbon nanotube, a carbonaceous compound other than the carbon nanotubes, a solvent, and the like are contained in a specific ratio, It can be seen that the electromagnetic wave absorbing effect is very excellent in the very high frequency region by maintaining a constant reflection coefficient and a transmission coefficient range in the region.

Accordingly, it can be seen from the above experimental results that the shielding material for a radar cover, which is a transceiver for a vehicle using the resin composition according to the present invention, is superior in electromagnetic wave absorption efficiency in a very high frequency region of an automobile environment.

As described above, when the shielding material for a vehicle radar transceiver is formed using the resin composition for electromagnetic wave absorption according to the present invention, it is possible to stabilize radar performance by absorbing noise reflected from a vehicle body or a bumper, It can be seen that the coefficient adjustment is effective in optimizing the performance of the vehicle radar.

100: Overview of electromagnetic wave absorption process
110: vehicle body 120: signal processing module
130: Bumper 140: Radar shield material
200: Horn Antenna 210: Absorbent material:

Claims (10)

a) 60 to 74% by weight of a polymeric resin;
b) 1 to 5% by weight of carbon nanotubes in the form of a rigid random coil having a static bending persistence of 100 nm to 500 nm;
c) 5 to 15% by weight of carbon black; And
A residual amount of a solvent,
Wherein the carbon nanotubes and the carbon black have a weight ratio of 1: 0.1 to 1: 100,
A surface resistance of 10 ⁶ to 10 ¹² (? / Sq)
Wherein the electromagnetic wave reflection coefficient is -6 dB or less and the electromagnetic wave transmission coefficient is -10 dB or less in the frequency range of 15 to 30 GHz.
The method according to claim 1,
The polymer resin may be selected from the group consisting of polybutylene terephthalate resin, polyethylene terephthalate resin, aromatic polyamide resin, polyamide resin, polycarbonate resin, polystyrene resin, polyphenylene sulfide resin, polysulfone resin, polyether sulfone resin, Resin, polyetheretherketone resin, polyarylate resin, polymethylmethacrylate resin, polypropylene resin, polyethylene resin, polyacrylonitrile butadiene styrene copolymer resin, polytetramethylene oxide-1,4-butanediol copolymer A resin, a styrene resin, a fluorine resin, a polyacrylonitrile resin, an acrylic resin, a polypyridine resin, a polytriazole resin, a polypyrrolidine resin, a polybenzothiazole resin, a polybenzimidazole resin, a polydibenzofuran resin, Urea resin, polyphosphazene resin, silicone Resins, epoxy resins, phenolic resins, polyurethane-based resin, and comprising a mixture thereof at least one element selected from the group consisting of electromagnetic wave-absorbing resin composition.
The method according to claim 1,
The carbon nanotubes may be single-walled, double-walled, thin multi-walled, multi-walled, multi-walled, , Wherein the composition is selected from the group consisting of polyvinyl alcohol and polyvinyl alcohol.
delete delete The method according to claim 1,
An inorganic filler, a coupling agent, and a lubricant. The electromagnetic wave absorptive resin composition according to claim 1, further comprising at least one member selected from the group consisting of an inorganic filler, a coupling agent, and a lubricant.
delete A molded article produced by extrusion, injection molding or thermoforming of the electromagnetic wave absorbing resin composition according to any one of claims 1 to 6.
9. The method of claim 8,
Wherein the molded article is an electromagnetic wave absorber for a vehicle.
10. The method of claim 9,
Wherein the electromagnetic wave absorber for a vehicle is a shielding material for a cover of a radar transceiver.

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