KR101740275B1

KR101740275B1 - Resin composition for electromagnetic interference shielding

Info

Publication number: KR101740275B1
Application number: KR1020150069962A
Authority: KR
Inventors: 박병철; 한진수; 김세권; 유문식
Original assignee: 한화컴파운드 주식회사; 주식회사 유라코퍼레이션
Priority date: 2015-05-19
Filing date: 2015-05-19
Publication date: 2017-05-26
Also published as: KR20160136146A

Abstract

The present invention relates to a composite resin composition for shielding electromagnetic waves. More specifically, the present invention relates to a composite resin composition for shielding electromagnetic interference comprising a polyamide resin, a nickel nanoparticle, a carbon fiber and a carbon black. The composite resin composition is excellent in electrical conductivity and low in surface resistance and suitable for EMI shielding. Is excellent in stability and excellent in economy and productivity because post processing is unnecessary, and is capable of replacing metal materials such as magnesium and aluminum.

Description

Technical Field [0001] The present invention relates to a resin composition for electromagnetic interference shielding,

Computers, mobile phones, etc., have been rapidly developed, miniaturized, and lightened. As a result, electronic components are highly integrated and the signal processing speed is increasing. One of the important factors that greatly determine the operation and reliability of such electronic products and components is electromagnetic interference (EMI).

These electromagnetic interference phenomena are manifested in various ways ranging from computer malfunctions to factory firing accidents. Furthermore, research results that have negative effects on the human body have been announced, thus strengthening regulations in Korea and other countries around the world.

Electromagnetic compatibility (EMC) means that the electromagnetic noise generated inside the electronic equipment is prevented from affecting the outside, and the inside of the electronic equipment is protected from electromagnetic noise generated in the external environment.

With the rapid development of electronic devices, the necessity of EMI / EMC-related materials and parts is greatly increased, and related technologies are developed and various applications are being made. In particular, in the case of an EV / PHEV vehicle, which is an affluent light vehicle, the operating voltage has been conventionally increased from 12V to 900V, and a technology for effectively shielding electromagnetic waves is further required.

EMI shielding effectiveness of electromagnetic waves can be expressed by the following equation (1).

[Equation 1] S.E. (Shielding effectiveness) = R + A + B

In the above Equation 1, R denotes the surface reflection of the electromagnetic wave, A denotes the internal absorption of the electromagnetic wave, and B denotes the loss through the multiple reflection.

Conventionally, metal is mainly used as a method for shielding electromagnetic waves. Such a metal material is produced by die-casting and plating and has to be subjected to a complicated process, so that it is disadvantageous in terms of production cost and productivity in the recent years that require high productivity.

On the contrary, the electromagnetic wave shielding material applying the polymer composite resin is a very economical method in terms of production cost and productivity because it can be produced only by the injection process of the composite resin. Especially, conductive composite resin, which has been widely used as a substitute for metals in energy, automobile, aerospace, and home appliance fields, has been applied as a shielding resin.

However, in the case of using the polymer composite resin, since the electrical conductivity is lower than that of the metal material, it is important to improve the surface reflection and the internal absorption among the items shown in the above-mentioned formula (1). Therefore, in the case of the composite resin, even if the same material is used, the electromagnetic wave shielding efficiency is lowered when the thickness is reduced. In order to increase the electromagnetic wave shielding efficiency of the composite resin, it is necessary to increase the R value by lowering the surface impedance (by increasing the electrical conductivity) and to increase the A value by inducing a large amount of electromagnetic wave scattering / absorption in the inside to form a high efficiency electromagnetic wave shielding composite resin have.

Accordingly, a method of replacing the thermoplastic resin that is easy to mold, has excellent molding accuracy, and is excellent in economy and productivity compared to the metal materials has been proposed. The metal replacement resin currently developed has a disadvantage in that the electromagnetic shielding effect is about 30dB (@ 1 GHz), and the EMI shielding property is significantly lower than that of metal. In order to increase the shielding property, there is a problem that the electric conductivity is too low even when it is used as a material of electronic devices because of the low fluidity, difficulty in practical application, and high surface resistance when the fiber content is high.

Therefore, it is necessary to develop new materials that can replace existing magnesium and aluminum materials because of excellent fluidity, impact strength and rigidity, excellent electric conductivity and shielding performance.

Korean Patent Registration No. 10-0789103.

The present invention for solving the above problems is to provide a composite resin composition having excellent injection moldability and excellent electromagnetic wave shielding effect by mixing a polyamide resin with carbon fiber, carbon black and nickel nanoparticles to increase miscibility .

The present invention provides a highly rigid composite resin composition for shielding electromagnetic waves, which has excellent mechanical strength and can replace a conventional metal material.

It is another object of the present invention to provide a molded article produced using the composite resin composition for shielding electromagnetic interference of the present invention.

In order to achieve the above object,

A composite resin composition for shielding electromagnetic interference is provided comprising, based on 100 parts by weight of a polyamide resin, 5 to 15 parts by weight of nickel nanoparticles, 25 to 45 parts by weight of carbon fibers, 1 to 10 parts by weight of carbon black and 0.1 to 10 parts by weight of additives do.

In the composite resin composition for shielding electromagnetic interference according to the present invention, the polyamide resin may be at least one selected from nylon 6, nylon 66, nylon 46, nylon 610, nylon 612, nylon 11 and nylon 12,

The carbon fibers may be chopped carbon fibers whose surface is coated with a polyamide resin or a polyurethane resin. The carbon fibers may further include carbon nanotubes.

The additive of the present invention provides at least one selected from the group consisting of an antioxidant, a lubricant, a compatibilizer, a colorant, a releasing agent, a flame retardant, a plasticizer and an antioxidant.

The present invention also provides a molded article produced by extrusion, injection molding or cast molding of the composite resin composition for shielding electromagnetic interference according to the present invention, for example , the molded article can be used for automobile high voltage connector applications.

INDUSTRIAL APPLICABILITY The electromagnetic wave shielding composite resin composition of the present invention is excellent in mechanical strength and conductivity and low in surface resistance, and is suitable for EMI shielding, has excellent fluidity and moldability, and is excellent in economy and productivity.

Further, the composite resin composition for shielding electromagnetic wave of the present invention can be used for automobile high voltage connector.

Hereinafter, the composite resin composition for shielding electromagnetic interference according to the present invention will be described in detail.

The composite resin composition of the present invention provides a composite resin composition for shielding electromagnetic interference comprising a polyamide resin, nickel nanoparticles, carbon fiber, carbon black and an additive.

The composite resin composition of the present invention comprises 5 to 15 parts by weight of nickel nanoparticles, 25 to 45 parts by weight of carbon fibers, 1 to 10 parts by weight of carbon black and 0.1 to 10 parts by weight of additives relative to 100 parts by weight of polyamide resin.

Examples of the polyamide resin include nylon 6, nylon 66, nylon 46, nylon 610, nylon 612, nylon 11, nylon 12, and the like. Of these, nylon 6 or nylon 66 can be preferably used. The polyamide resin is excellent in stiffness, toughness, abrasion resistance, chemical resistance, oil resistance and moldability, and can be applied to fuel system components and electromagnetic shielding electronic parts of automobiles.

The polyamide resin may have a weight average molecular weight of 10,000 to 200,000 g / mol, preferably 30,000 to 100,000 g / mol. There is an advantage in that both the flowability and the mechanical properties are excellent within the above range.

In the present invention, 5 to 15 parts by weight of nickel nanoparticles may be added to 100 parts by weight of the polyamide resin. Within this range, the effect of conductivity is enhanced and the surface resistance is improved. The shape of the nickel nanoparticles may be nickel powder, nickel beads, and the like, but is not limited thereto. Among them, when used in the form of a nickel powder, the average particle diameter may be 20 to 800 nm. There is an advantage that the electromagnetic wave shielding efficiency is increased in the above range.

The carbon fiber used in the present invention is a carbon fiber having conductivity and is lighter than metal and has an advantage of being superior in elasticity and strength as compared with metal such as iron.

The content of the carbon fibers is preferably 25 to 45 parts by weight based on 100 parts by weight of the polyamide resin. Within the above range, excellent physical properties such as heat resistance and rigidity and electrical conductivity can be obtained.

The carbon fiber may be made of a pitch, rayon or polyacrylonitrile (PAN) system, and the length of the carbon fiber may be 1 to 20 mm.

As the carbon fiber, carbon fibrils, carbon fibers, carbon nanotubes and the like can be used.

The carbon fiber of the present invention has a carbon content of 90 wt% or more, more preferably a chopped shape having a length of 3 to 12 mm.

The surface of the carbon fiber of the present invention may be coated with a polyamide or polyurethane resin. Or 0.01 to 1 part by weight of a polyurethane resin may be added to 100 parts by weight of carbon fibers.

The surface-treated carbon fiber of the present invention has an advantage of remarkably improving mechanical properties such as electrical conductivity and rigidity. The molecular weight of the surface-treated resin of the present invention is preferably from 5,000 to 1,000,000.

The carbon fiber of the present invention may further comprise a supercritical carbon nanotube. Can be obtained by surface treating the carbon nanotubes only with dissolved oxygen dissolved in water at a pressure of 50 to 400 atm and a temperature of 100 to 600 ° C. The carbon nanotube may be a single wall, a double wall, or a multiple wall, or a combination thereof. Preferably multi-walled carbon nanotubes. When the carbon nanotubes are included, they can have excellent electromagnetic wave shielding performance.

The present invention is used for securing process stability and improving electromagnetic wave shielding effect by including carbon black. The present invention can be used as 1 to 10 parts by weight of carbon black per 100 parts by weight of polyamide resin, If the amount is less than 10 parts by weight, the effect is insignificant. If the amount is more than 10 parts by weight, moldability is poor and injection molding is impossible.

The carbon black is not particularly limited as long as it is a commercialized product such as furnace black, acetylene black, and ketjen black. However, it is preferable to select a product having a large specific surface area and good mixing property with the polymer resin.

The present invention may further include additives such as an antioxidant, a lubricant, a compatibilizer, a colorant, a release agent, a flame retardant, a plasticizer, and an antioxidant, and these may be used alone or in combination. The amount of the additive to be used may be appropriately adjusted depending on various factors including the desired end use and characteristics.

The additive may be contained in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the polyamide resin. In the present invention, 0.1 to 1 part by weight of an antioxidant is contained, 0.1 to 1 part by weight of PE-wax is used as a lubricant, and 0.1 to 1 part by weight of a compatibilizer is added to improve the miscibility of the resin.

Conventional molding methods can be applied to the composite resin composition for shielding electromagnetic interference of the present invention. For example, each component may be put into an extruder to produce a pellet. The pellet may be molded into a molded product suitable for use as a sheet, film, or structure through injection molding, compression molding, casting, or the like.

In addition, the molded article can be used for automobile high-voltage connector applications due to its high conductivity and electromagnetic shielding effect.

Hereinafter, the present invention will be described in more detail by way of examples. However, the following examples are only the preferred embodiments of the present invention, and the present invention is not limited to the following examples.

The specifications of each component used in the following Examples and Comparative Examples are as follows

Polyamide-Nylon 6: Hyosung's 1027BRT was used.

Polyamide-Nylon 66: 50BWFS from Ascend was used.

Carbon Fiber (C / F): ACECA-6PA from Ace Co., Ltd. was used as a chopped CarbonFiber with a length of 6 mm, which was nylon 6 sizing.

Carbon black (C / B): HI Black 50L (20 nm) manufactured by Evonic Corporation was used.

Ni Nano Powder: Ni nanopowder (Ni 99.9 wt%, 70 nm) manufactured by US Research Nanomaterials Co., Ltd. was used.

Al Nano Powder: Al Nano Powder (Al 99wt%, 100nm) manufactured by US Research Nanomaterials Co., Ltd. was used.

Cu Nano Powder: Cu Nano Powder (Cu 99.9 wt%, 70 nm) manufactured by US Research Nanomaterials Co., Ltd. was used.

Antioxidant: IRGANOX1010 of CIBA chemical was used as an antioxidant.

Lubricant: PE-Wax was used by LC-102N manufactured by Ryan Chemtech.

Commercializer: DSL-400 from Solusys was used.

In the following Examples and Comparative Examples, the methods for evaluating properties are as follows.

(1) Tensile strength: Evaluated according to ASTM D790 under the condition of 1.27 mm / min, and the unit is kgf / cm ² .

(2) Izod impact strength (notched): Evaluated at 23 캜 according to ASTM D256 at a thickness of 3.2 mm, and the unit is kgfcm / cm.

(3) Surface resistivity: It was evaluated by 4 point probe method for the injection specimen of 1 t thickness, and the unit is Ω / sq.

(4) EMI shielding property (SE): Electromagnetic shielding performance of a sample (6 × 6) having a thickness of 510 kHz to 108 MHz and a thickness of 1 t was measured at 23 ° C. in accordance with EMI D257 at 510 kHz to 1.5 GHz, Is dB.

The composite resin of the present invention has a tensile strength of 1000 kgf / cm ² or more according to ASTM D790, an EMI shielding of 50 dB or more, more preferably 65 dB or more, and a surface resistance of 1 Ω / sq or less by EMI D257.

[Examples 1 to 4]

Each component was mixed in the amounts shown in Table 1 below. First, a polyamide resin was charged into a primary raw material inlet of a twin-screw extruder (L / D = 40, Φ = 27 mm) heated to 250 ° C. and a Ni nano powder (average particle diameter: 70 nm) 1 to 10 parts by weight of Carbon Black (average particle diameter: 20 nm), 0.5 part by weight of antioxidant, 0.3 part by weight of PE wax and 0.5 part by weight of compatibilizer were fed into a secondary inlet And 25 to 45 parts by weight of carbon fiber was added to the polyamide resin through a side feeder through a third inlet located at the end of the twin-screw extruder to prepare a composite resin composition through a heat-melt kneading process. This was dried in a hot air drier at 100 DEG C for 4 hours.

The pellets were manufactured at a injection temperature of 260 ° C and a specimen for application evaluation such as EMI and surface resistivity was prepared using a 150 ton injection machine. These specimens were allowed to stand for 48 hours at 23 ° C. and 50% relative humidity, and their properties were evaluated by the above-mentioned method. The results are shown in Table 1.

[Examples 5 to 6]

Except that a polyurethane resin solution other than Nylon 6 was used and carbon fibers subjected to sizing treatment (ACECA-PU manufactured by Acecotech Co., Ltd.) were used. The specimens were allowed to stand at 23 ° C and 50% RH for 48 hours. The properties of the specimens were evaluated by the above-mentioned method. The results are shown in Table 1.

[Example 7]

Except that 30 parts by weight of a supercritically treated multi-walled carbon nanotube (CM-130, manufactured by Hanwha Chemical Co., Ltd.) was added (carbon fiber 70: carbon nanotube 30) to 100 parts by weight of total carbon fibers. Were prepared in the same manner. The specimens were allowed to stand at 23 ° C and 50% RH for 48 hours. The properties of the specimens were evaluated by the above-mentioned method. The results are shown in Table 1.

Example
One Example
2 Example
3 Example
4 Example
5 Example
6 Example
7 Nylon6 100 100 100 100 Nylon 66 100 100 100 Ni 5 15 5 10 10 15 10 Cu Al C / F 25 45 30 30 40 (PU) 40 (PU) 40 (CNT 30%) C / B 3 3 10 5 10 10 10 Antioxidant 0.5 0.5 0.5 0.5 0.5 0.5 0.5 slush 0.3 0.3 0.3 0.3 0.3 0.3 0.3 Compatibilizer 0.5 0.5 0.5 0.5 0.5 0.5 0.5 The tensile strength 1000 1350 1350 1378 1110 1480 1210 Impact strength 7 10 8 8.8 8.5 9.0 8.1 Surface resistivity 8.0x10 ^ -1 2.0 x 10 -2 3.5x10 ^ -1 1.0 x 10 ^ -1 8.5 x 10 -2 4.5 x 10 -2 5.5x10 -2 S.E. 65 110 80 90 120 125 115

[Comparative Examples 1 to 6]

Each component was mixed in the amounts shown in Table 2 below. First, a polyamide resin was charged into a primary feed inlet of a twin-screw extruder (L / D = 40, Φ = 27 mm) heated to 250 ° C., and Ni nano powder, Carbon Black, antioxidant, PE wax, , And the carbon fiber was fed through a side feeder to a third inlet located at the end of the twin-screw extruder, and a composite resin composition was prepared through a heat-melt kneading process. This was dried in a hot air drier at 100 DEG C for 4 hours. The pellets were manufactured at a injection temperature of 260 ° C and a specimen for application evaluation such as EMI and surface resistivity was prepared using a 150 ton injection machine. These specimens were allowed to stand at 23 ° C and 50% RH for 48 hours, and their physical properties were evaluated by the above-mentioned method.

[Comparative Example 7]

Except that 15 parts by weight of Al powder was used instead of Ni nano powder with respect to 100 parts by weight of polyamide resin. The specimens were allowed to stand at 23 ° C and 50% relative humidity for 48 hours. The properties of the specimens were evaluated by the above method. The results are shown in Table 2.

[Comparative Example 8]

Except that 15 parts by weight of Cu powder was used instead of Ni nano powder with respect to 100 parts by weight of the polyamide resin. The specimens were allowed to stand at 23 ° C and 50% relative humidity for 48 hours. The properties of the specimens were evaluated by the above method. The results are shown in Table 2.

Comparative Example
One Comparative Example
2 Comparative Example
3 Comparative Example
4 Comparative Example
5 Comparative Example
6 Comparative Example
7 Comparative Example
8 Nylon6 100 100 100 100 100 100 Nylon 66 100 100 Ni 4 17 15 10 10 10 Cu 15 Al 15 C / F 30 25 20 50 30 40 30 30 C / B 10 5 5 5 0 15 10 10 Antioxidant 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 slush 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 Compatibilizer 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 The tensile strength 1150 780 750 Defective molding 1100 Defective molding 1200 1100 Impact strength 8 5.5 5.5 8 7 7 Surface resistivity 2.2 4.6 x 10 ^ -1 8.7 x 10 ^ -1 1.3x10 ^ -1 2.3x10 ^ 0 4.6 x 10 ^ -1 5.7 x 10 ^ 4 6.0x10 ^ 5 S.E. 40 65 60 130 40 145 30 30

The results of Tables 1 and 2 show that Examples 1 to 7 produced by the method of the present invention had a tensile strength of 1000 kgf / cm ² or more, an EMI shielding effect of 65 dB or more, a surface resistance of 1.0 Ω / sq or less.

The results of Comparative Examples 1 and 2 show that the content of the nickel nanoparticles is less than 5 parts by weight and more than 15 parts by weight, respectively, and thus exhibits a low tensile strength and a surface resistivity. The results of Comparative Examples 3 and 4 show that when the content of carbon fibers is less than 20 parts by weight and more than 50 parts by weight of the present invention, low tensile strength and moldability are deteriorated and the resultant product can not be formed into a molded product.

The results of Comparative Examples 5 and 6 indicate that the content of carbon black is less than 1 part by weight and less than 15 parts by weight of the present invention, the surface resistivity is lowered, the shielding efficiency is lowered, the moldability is lowered, Respectively.

In Comparative Examples 7 and 8, the use of copper and aluminum nanoparticles instead of the nickel nanoparticles of the present invention resulted in lower surface resistivity and lower electromagnetic wave shielding efficiency.

Having described specific portions of the present invention in detail, those skilled in the art will appreciate that these specific embodiments are merely preferred embodiments and that the scope of the present invention is not limited thereto Will be clear.

Claims

To 100 parts by weight of a polyamide resin having a weight average molecular weight of 10,000 to 200,000 g / mol,
5 to 15 parts by weight of nickel nanoparticles having an average particle diameter of 20 to 800 nm, 25 to 45 parts by weight of carbon fibers, 1 to 10 parts by weight of carbon black and 0.1 to 10 parts by weight of an additive.

The method according to claim 1,
Wherein the polyamide resin is at least one selected from nylon 6, nylon 66, nylon 46, nylon 610, nylon 612, nylon 11, and nylon 12.

The method according to claim 1,
Wherein the surface of the carbon fibers is coated with a polyurethane resin.

The method according to claim 1,
Wherein the carbon fibers further comprise carbon nanotubes.

The method according to claim 1,
Wherein the carbon fibers have a length of 1 to 20 mm.

The method according to claim 1,
Wherein the carbon fiber is a chopped carbon fiber.

The method according to claim 1,
Wherein the additive is at least one selected from an antioxidant, a lubricant, a compatibilizer, a colorant, a release agent, a flame retardant, a plasticizer and an antioxidant.

A molded article produced by extrusion, injection molding or casting the electromagnetic wave shielding composite resin composition according to any one of claims 1 to 7.

9. The method of claim 8,
The molded article is used for automotive high voltage connector applications.