KR20130077705A - High modulus and impact composite for emi shielding - Google Patents

Abstract

PURPOSE: A highly rigid electromagnetic interference shielding composite is provided to excellent dimensional stability by replacing an existing metal material. CONSTITUTION: A thermoplastic resins (40) of a highly rigid electromagnetic interference shielding composite forms a continuous phase. A semi-dispersed phase is formed by a first metal filler (10), a second metal filler (20) and a surface-treated carbon fiber (30). The first filler continuously or discontinuously surrounds the surface of the second metal filler. The surface-treated carbon fiber is treated by resin and metal and the treated resin consists of polyamide and epoxy resin. The melting point of the thermoplastic resin, the first metal filler and the second metal filler satisfies Tma-30°C> Tmb and Tma+500°C < Tmc, respectively.

Description

[0001] HIGH MODULUS AND IMPACT COMPOSITE FOR EMI SHIELDING [0002]

The present invention relates to a high rigidity electromagnetic wave shielding composite material. More particularly, the present invention relates to a high-rigidity electromagnetic wave shielding composite material having excellent mechanical strength and EMI shielding property, which can reduce the production cost by replacing existing metal materials and has excellent processability.

Electromagnetic waves are known to cause noise and malfunctions in nearby parts or devices, and also have harmful effects on the human body due to noise caused by electrostatic discharge. In recent years, the possibility of generating electromagnetic waves has been rapidly increasing due to high efficiency, high power consumption, and highly integrated electric / electronic products. Regulation of electromagnetic waves has been strengthened not only in advanced countries but also in Korea.

Conventionally, there is a method of using a metallic material as a method for shielding electromagnetic waves. For example, IT brackets used in portable display products such as mobile phones, notebooks, PDAs and other mobile items require high rigidity and EMI shielding because they protect LCDs, shield electromagnetic waves, and serve as frames . In recent years, metals such as magnesium, aluminum, and stainless steel have been mainly used as materials for brackets and frames. However, such a metal material has an advantage that it can effectively block electromagnetic waves, but it is produced by a die-casting method and has a high production cost and a high defect rate.

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 modulus of currently developed metal substitute resin is below FM 20GPa and electromagnetic wave shielding effect is about 30dB (@ 1GHz), which has a disadvantage that rigidity and EMI shielding are remarkably lower than metal. A method of raising the fiber content to raise the modulus has been proposed. However, when the fiber content is high, the impact strength is low, the fluidity is low, and it is difficult to apply because of difficulty in practical application. There is a problem that the conductivity is too low to use.

In addition, high filler loading is difficult in low flow bases. In recent years, products having a high modulus and an electromagnetic shielding effect of 30 dB or more have been developed using carbon fibers of 50% or more, but they are insufficient to replace metals and have difficulty in processing. Furthermore, there is a problem in that the conductivity is low to use such a material as a material of an electronic device. For example, when a general mobile phone bracket is used, problems such as lowered grounding performance and antenna performance deteriorate.

In general high-stiffness resins, the surface resistance is lowered by conducting conductive plating in order to solve this problem. However, the cost is increased due to the plating process and the subsequent process, and the surface is peeled off during long-term use.

Therefore, it is necessary to develop a new material which has excellent fluidity, impact strength and rigidity, excellent conductivity and shielding performance, and can replace the existing metal material.

An object of the present invention is to provide a high rigidity electromagnetic wave shielding composite excellent in mechanical strength.

Another object of the present invention is to provide a highly rigid electromagnetic shielding composite suitable for EMI shielding because of its excellent conductivity and low surface resistance and volume resistance.

It is still another object of the present invention to provide a high-rigidity electromagnetic wave shielding composite excellent in fluidity and moldability.

Another object of the present invention is to provide a high-rigidity electromagnetic wave shielding composite which is free of post-processing and excellent in economy and productivity.

It is still another object of the present invention to provide a high rigidity electromagnetic wave shielding composite excellent in dimensional stability.

Another object of the present invention is to provide a high strength electromagnetic wave shielding composite which can replace existing metal materials.

The technical objects to be achieved by the present invention are not limited to the above-mentioned technical problems, and other technical subjects which are not mentioned can be understood by those skilled in the art from the following description.

One aspect of the present invention relates to a high rigidity electromagnetic wave shielding composite. The composite material comprises (A) a thermoplastic resin; (B) a first metal filler; (C) a second metal filler; And (D) surface-treated carbon fibers, wherein the surface-treated carbon fibers (D) are surface-treated with a resin or a metal, the surface-treated resin is a polyamide or an epoxy resin, and the thermoplastic resin (A), the melting point of the first metal filler (B) and the melting point of the second metal filler (C) satisfy the following formula 1:

[Formula 1]

Tma-30 ° C> Tmb, Tma + 500 ° C <Tmc

(Tmc is the melting point (占 폚) of the second metal filler (C)). The melting point (占 폚) of the thermoplastic resin (A), Tmb is the melting point (占 폚) of the first metal filler (B)

The thermoplastic resin (A) may be a crystalline thermoplastic resin.

The second metal filler (C) may be in the shape of a sphere, flake or egg shape.

In an embodiment, the weight ratio of the first metal filler (B) and the second metal filler (C) may be 1: 1 to 3: 1.

The surface-treated carbon fiber (D) may have a diameter of 3 to 10 mu m.

The metal surface-treated to the carbon fiber (D) may include at least one metal selected from the group consisting of aluminum, stainless steel, iron, chromium, nickel, black nickel, copper, silver, gold and platinum.

(A) from 10 to 84% by weight of a thermoplastic resin; (B) 5 to 35% by weight of a first metal filler; (C) 0.5 to 30% by weight of a second metal filler; And (D) 10 to 60% by weight of surface-treated carbon fibers.

The content of the surface-treated carbon fibers (D) may be larger than the content of the thermoplastic resin (A).

The composite material may further include additives such as a flame retardant, an impact modifier, a plasticizer, a coupling agent, a heat stabilizer, a light stabilizer, an inorganic filler, a releasing agent, a dispersant, a dripping inhibitor and a weathering stabilizer.

According to another aspect of the present invention, there is provided a high-rigidity electromagnetic shielding composite material, wherein the thermoplastic resin forms a continuous phase, the first metal filler, the second metal filler, and the surface-treated carbon fibers form a dispersed phase on the continuous phase, The melting point of the metal filler is lower than the melting point of the second metal filler by 700 DEG C or more and the first metal filler is continuously or discontinuously surrounded on the surface of the second metal filler and has a melting point of 3.2 mm according to ASTM D790 The flexural modulus at the thickness is at least 25 GPa, and at 1 GHz the surface resistance can be less than 3.0 Ω · cm.

Disclosed is a resin composition which is excellent in mechanical strength and conductivity, low in surface resistance and volume resistance, suitable for EMI shielding, excellent in fluidity and moldability, is free of post-processing, excellent in economy and productivity, excellent in dimensional stability, The present invention has the effect of providing a high-rigidity electromagnetic wave shielding composite that can be replaced.

FIG. 1 is a schematic diagram of a high-rigidity electromagnetic wave shielding composite according to one embodiment of the present invention.

The high rigidity electromagnetic wave shielding composite of the present invention comprises (A) a thermoplastic resin; (B) a first metal filler; (C) a second metal filler; And (D) surface-treated carbon fibers.

Hereinafter, each of the above components will be described in detail.

(A) a thermoplastic resin

The thermoplastic resin that can be used in the present invention is not particularly limited. Examples of the resin include polyamide resins, polyester resins, polyacetal resins, polycarbonate resins, poly (meth) acrylate resins, polyvinyl chloride resins, polyether resins, polysulfide resins, polyimide resins A resin, a polysulfone resin, a polyolefin resin, an aromatic vinyl resin, and the like may be used, but are not limited thereto. These may be used alone or in combination of two or more.

Preferably, the thermoplastic resin is a crystalline thermoplastic resin, more preferably a polyamide-based resin or a polyester-based resin.

As the polyamide-based resin, an aliphatic polyamide resin, an aromatic polyamide resin containing an aromatic group in the main chain, or a copolymer or a mixture thereof may be used. In a specific example, NYLON 6, NYLON 66, NYLON 46, NYLON 610, NYLON 612, NYLON 66/6, NYLON 6/6 T, NYLON 66/6 I, NYLON 6T, NYLON 9T, NYLON 10T, NYLON MXD 6, NYLON 6I / May be used, but are not necessarily limited thereto. An aromatic polyamide resin containing an aromatic group in its double main chain can be preferably used. When the aromatic group is contained in the main chain in this manner, higher rigidity and strength can be imparted.

In one embodiment, the polyamide resin may have a glass transition temperature (Tg) of 60 to 120 ° C, preferably 80 to 100 ° C. It is possible to obtain excellent balance of fluidity, rigidity and low moisture absorptivity in the above range.

The polyamide resin may have a number 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 in the above range.

As the polyester resin, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, or the like may be used, but not always limited thereto.

As the polyacetal-based resin, a polyoxymethylene-based resin may be used, but the present invention is not limited thereto.

The polycarbonate-based resin may have a form such as a linear polycarbonate resin, a branched polycarbonate resin, or a polyester carbonate copolymer resin, and preferably a bisphenol A-based polycarbonate may be used.

As the poly (meth) acrylate-based resin, an aromatic (meth) acrylate polymer, an aliphatic (meth) acrylate polymer, a copolymer or a mixture thereof may be applied. In a specific example, a homopolymer of methyl methacrylate is used, or a copolymer of methyl methacrylate and another vinyl monomer may be used. Examples of the vinyl monomer include methacrylic acid esters including ethyl methacrylate, propyl methacrylate, butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate and benzyl methacrylate; Acrylic esters including methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate; Unsaturated carboxylic acids including acrylic acid and methacrylic acid; Acid anhydrides including maleic anhydride; Esters containing hydroxy groups including 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate and monoglycerol acrylate, and the like.

Examples of the polyolefin-based resin include polyethylene, polypropylene, polybutylene, and the like. Copolymers or mixtures thereof may also be used. In addition, their adducttic, isotactic, and syndiotactic structures can all be applied.

As the aromatic vinyl resin, polystyrene, HIPS, ABS, SAN, ASA, MABS, or a combination thereof may be used.

In the present invention, the thermoplastic resin (A) forms a continuous phase and is used in an amount of 10 to 84% by weight, for example, 30 to 80% by weight, preferably 35 to 75% by weight, more preferably 35 to 55% % &Lt; / RTI &gt; by weight. It is excellent in modulus, strength, EMI shielding performance and formability in the above range.

(B) a first metal filler

The first metal filler (B) used in the present invention may be a low melting metal having a melting point lower than the melting point of the thermoplastic resin (A). As a result, the thermoplastic resin (A) is melted together during processing such as melt extrusion, and the second metal filler (C) to be described later is wrapped.

The melting point of the thermoplastic resin (A), the first metal filler (B), and the second metal filler (C) satisfy the following formula 1:

[Formula 1]

Tma -30 ° C> Tmb , Tma +500 ° C < Tmc

(Tmc is the melting point (占 폚) of the second metal filler (C)). The melting point (占 폚) of the thermoplastic resin (A), Tmb is the melting point (占 폚) of the first metal filler (B)

The first metal filler B preferably has a solidus temperature (solidus temperature) lower than the composite process temperature of the thermoplastic resin (A). Preferably, the solidification temperature of the first metal filler (B) is 30 ° C or more lower than the process temperature of the thermoplastic resin (A) in terms of forming a network between the composite material manufacturing process and the filler, High stability is good.

Preferably, the melting point of the first metal filler (B) may be 185 to 300 캜, preferably 190 to 250 캜, more preferably 200 to 245 캜.

The first metal filler (B) preferably has conductivity. For example, the first metal filler (B) may have a conductivity of 1.0 x 10 ⁶ s / m to 10 x 10 ⁶ s / m. And has excellent chargeability in the above range.

Examples of the first metal filler (B) include bismuth, polonium, cadmium, gallium, indium, lead, tin or an alloy thereof. An alloy containing a main component selected from the group consisting of tin, lead and combinations thereof and a subcomponent selected from the group consisting of copper, aluminum, nickel, silver, germanium, indium, zinc and combinations thereof have. The first metal filler may be in the form of a partially alloyed refractory metal, and in any case, satisfy the condition of the formula (1).

In the present invention, the first metal filler (B) is contained in an amount of 5 to 35 wt%, for example, 7 to 30 wt%, preferably 10 to 25 wt%, and more preferably 10 to 20 wt% . In the above range, conductivity and flowability, impact strength and balance of flexural modulus can be obtained.

(C) a second metal filler

The second metal filler may have higher conductivity and melting point than the first metal filler (B). Preferably, a metal having a melting point higher by 700 ° C or more than the first metal filler (B) may be used.

In a specific example, the second metal filler (C) may have a melting point of 950 ° C or higher, for example, 1000 to 2000 ° C.

The second metal filler (C) may have a conductivity of 1.0 × 10 ⁷ s / m to 10 × 10 ⁷ s / m. And has excellent chargeability in the above range.

Examples of the second metal filler C include stainless steel, iron, chromium, nickel, black nickel, copper, gold, platinum, palladium, cobalt, titanium, vanadium, rhodium and alloys of two or more thereof. These may be used alone or in combination of two or more. In one embodiment it may be an alloy of iron-chromium-nickel. The second metal filler may be in the form of a partially alloyed low-melting-point metal, and in any case, satisfies the condition of the formula (1).

The shape of the second metal filler (C) may be a metal powder, a spherical metal including a metal bead, a metal fiber, a metal flake, a metal on a branch, and the like. These may be used alone or in combination of two or more. A double sphere or flake shape is preferred.

When the shape of the second metal filler (C) is used in the form of metal powder or metal beads, the average particle diameter may be 30 to 300 mu m. In the above range, feeding is advantageous when extruded.

When the metal filler is used in the form of a metal fiber, it may have a length of 0.1 mm to 15 mm and a diameter range of 10 to 100 탆. The metal fibers may have a density of 0.7 to 6.0 g / ml. Proper feeding can be maintained during extrusion processing in the above range.

When the shape of the metal filler is used in the form of a metal flake, the average size may be 50 to 500 mu m. In this range, proper feeding can be maintained during extrusion processing.

When using metal in the form of a metal filler, the average size may be between 5 and 80 mu m. The networking of the metal filler and the carbon fiber can be maintained within the above range, and the electrical conductivity is improved.

The weight ratio of the first metal filler (B) and the second metal filler (C) may be 1: 1 to 3: 1, preferably 1.1: 1 to 2: 1. And has better EMI shielding, high rigidity and high impact resistance in the above range.

In the present invention, the second metal filler (C) is contained in an amount of 0.5 to 30 wt%, for example, 1 to 25 wt%, preferably 10 to 20 wt%, and more preferably 10 to 15 wt% . In the above range, conductivity and flowability, impact strength and balance of flexural modulus can be obtained.

(D) Surface treated carbon fiber

The carbon fiber used in the present invention is a carbon fiber having conductivity, and the surface of the carbon fiber is treated with resin or metal.

In the specific examples, the carbon fibers produced from the PAN system or the pitch system may be used.

The average diameter of the surface-treated carbon fibers may be 3 to 10 mu m, preferably 3.5 to 7 mu m. Excellent physical properties and conductivity can be obtained within the above range.

The carbon fibers used in the production of the high-rigidity electromagnetic wave shielding composite material of the present invention may be short fiber, long fiber or rod type. In another example, the carbon fibers may be bundled.

The surface of the carbon fibers of the present invention can be sized with polyamide or epoxy resin. The carbon fiber surface-treated with such a specific resin can easily disperse the carbon fiber and can reduce the number of single fibers of the carbon fiber during processing, and has the advantage of improving physical properties such as rigidity and electrical conductivity through such characteristics. In this case, the sizing concentration may be 0.5 to 7.5%, preferably 1 to 5%. If it is lower than the above range, there may occur a deterioration in workability and a decrease in bending modulus due to single yarns of carbon fibers, and if it is higher, there is a drawback that physical properties such as electrical conductivity are deteriorated due to the problem of networking between carbon fibers. The sizing concentration can be determined by thermal analysis of TGA.

In a specific example, the polyamide resin can be preferably applied when the thermoplastic resin (A) forming the continuous phase is a polyamide resin. When the sizing agent is an epoxy resin, for example, an epoxy resin or a polyester resin may preferably be applied.

The carbon fibers of the present invention can be coated with a metal. The coating thickness is preferably 30 nm to 200 nm. If it is thinner than the above range, the carbon fibers may be unevenly wound due to desorption of the metal, and the electrical conductivity and flexural modulus may be lowered. If the thickness is too thick, the flexural modulus may be lowered due to the reduction of the carbon fiber content due to the increase in specific gravity .

In this case, the surface-treated metal is not particularly limited as long as it has conductivity, and aluminum, stainless steel, iron, chromium, nickel, black nickel, copper, silver, gold and platinum can be used. These may be used alone or in combination of two or more.

The surface-treated carbon fibers may be contained in an amount of 10 to 60% by weight, for example, 15 to 50% by weight, preferably 20 to 45% by weight, more preferably 25 to 40% by weight of the entire composite material. In the above range, conductivity and flowability, impact strength and balance of flexural modulus can be obtained.

In embodiments, the content of the surface-treated carbon fiber (D) may be greater than or equal to the content of the thermoplastic resin (A). Preferably, the weight ratio of the thermoplastic resin (A) to the surface-treated carbon fiber (D) may be 1: 1 to 1: 1.5. And has a balance of rigidity and moldability in the above range.

The ratio of the carbon fiber D to the first metal filler B and the second metal filler C may be selected from the group consisting of surface treated carbon fibers D and first and second metal fillers B + C) = 1.8 to 2.5: 1. Excellent physical property balance can be obtained in the above range.

The composite material may further include additives such as a flame retardant, an impact modifier, a plasticizer, a coupling agent, a heat stabilizer, a light stabilizer, an inorganic filler, a releasing agent, a dispersant, a dripping inhibitor and a weathering stabilizer. These may be used alone or in combination of two or more.

In the composite material of the present invention, a conventional molding method of a thermoplastic resin composition can be applied as it is. For example, the respective components are put into an extruder to produce pellets, and the pellets can be prepared in various forms by injection molding, compression molding, casting, or the like.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic diagram of an electromagnetic shielding composite according to one embodiment of the present invention. As shown in Fig. 1, the molded composite is formed by forming a thermoplastic resin 40 in a continuous phase, and forming a first metal filler 10, a second metal filler 20, 30 and the second metal filler 20 form a dispersed phase and the first metal filler 10 may be continuously or discontinuously surrounded on the surface of the second metal filler 20. [

The composite material of the present invention has a flexural modulus of 25 GPa or more at a thickness of 3.2 mm according to ASTM D790, an EMI shielding of 40 dB or more at 1 GHz according to ASTM D257, and a surface resistance of 3.0 Ω or less.

Since the composite material of the present invention has excellent electromagnetic wave shielding properties, conductivity, mechanical properties and moldability, it can be suitably applied to LCD protective brackets and various electromagnetic wave shielding materials of portable display products.

Hereinafter, the configuration and operation of the present invention through the preferred embodiment of the present invention will be described in more detail. It is to be understood, however, that the same is by way of illustration and example only and is not to be construed in a limiting sense.

Details that are not described herein will be omitted since those skilled in the art can sufficiently infer technically.

Example

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

(A) a thermoplastic resin

(A1) As a PA66 product having a melting point of 270 ° C, a ZYTEL 101 F product manufactured by Dupont Corporation was used.

(A2) T600 manufactured by Toyobo was used as a PA product having a melting point of 240 占 폚.

(B) First metal filler: SA35 of Duksan Hi-Metal was used as a solder powder having a melting point of 220 占 폚.

(C) Second metal filler: Silver coated cupper having a melting point of 1000 ° C or higher was used as the SCC of the pre-heated ST.

(D) Surface treated carbon fiber

(D1) HT C603 of ToHo Tenex Co., which was sizing with polyamide resin, sizing content of 3.5% and diameter of 7.2 ㎛, was used.

(D2) Nickel coated carbon fiber: Tenax MC of Toho Co. was used.

(D3) PANEX PX35CA0250-65 of Zoltek with sizing content of 2.75% and diameter of 7.2 탆, which was sizing with polyurethane resin, was used.

(F) Heat stabilizer and lubricant: IRGANOX1010 of CIBA chemical as a heat stabilizer and ethylene bis stearate as a lubricant were mixed at a ratio of 1: 1. And 0.5 parts by weight based on 100 parts by weight of the components (A) to (D).

Example  1 to 5 and Comparative example  1-4

The above components were mixed in the usual mixer at the contents shown in the following Table 1, extruded using a twin-screw extruder having L / D = 35 and Φ = 45 mm, and then extruded into pellets. The prepared pellets were dried at 100 ℃ for 4 hours in a hot air drier, and specimens were prepared for application evaluation such as measurement of physical properties and EMI / resistance at an injection temperature of 290 ℃. These specimens were left for 48 hours at 23 ° C and 50% relative humidity, and then their physical properties were measured according to the ASTM standard.

Assessment Methods:

(1) Flexural modulus: Evaluated according to ASTM D790 at a thickness of 3.2 mm at a rate of 1.4 mm / min, and the unit is GPa.

(2) Specific gravity: measured by ASTM D792.

(3) Spiral flow: 6oz Injection into a spiral mold having a thickness of 2 mm at a molding temperature of 320 DEG C, a mold temperature of 60 DEG C, an injection pressure of 50% and an injection speed of 70% mm) was measured.

(4) EMI shielding (dB): The sample was allowed to stand for 48 hours under a condition of 23 deg. C and a relative humidity of 50%, and electromagnetic wave shielding performance was measured for a sample (6X6) having a thickness of 2t at 1 GHz according to EMI257.

(5) Surface resistance: A copper tab having an area of 10 mm * 10 mm was manufactured and evaluated for 3.2 t thick injection specimens (Ω) using an asahi 4201 resistance meter.

(6) Volumetric resistance: A 3.2-m thick injection sample was evaluated in accordance with ASTM D257.

The results are shown in Tables 1 and 2.

Example 2 3 4 5 (A) a thermoplastic resin A1 30 30 35 35 35 A2 - - - - - (B) a first metal filler 20 20 20 15 17 (C) a second metal filler 10 10 15 10 8 (D) carbon fiber D1 40 - 30 20 20 D2 - 40 - 20 20 D3 - - - - - (F) Additive 0.5 0.5 0.5 0.5 0.5 Flexual Modulus (GPa) 26 26 26 28 27 importance 1.8 1.8 1.7 1.7 1.7 spiral (mm) 220 220 230 250 240 EMI Shielding Effect (dB) 56 61 49 50 49 Surface resistance (Ω) 1.8 1.5 2.3 2.2 2.2 Volumetric resistance (Ω · cm) 0.18 0.15 0.25 0.28 0.26

Comparative Example One 2 3 4 (A) a thermoplastic resin A1 40 40 30 - A2 - - - 30 (B) a first metal filler 20 - 20 20 (C) a second metal filler - 20 10 10 (D) carbon fiber D1 40 40 40 D2 - - - - D3 - - 40 - (F) Additive 0.5 0.5 0.5 0.5 Flexual Modulus (GPa) 29 28 23 24 importance 1.7 1.7 1.8 1.8 spiral (mm) 250 250 220 220 EMI Shielding Effect (dB) 40 41 42 38 Surface resistance (Ω) 3.8 4.0 2.3 5.0 Volumetric resistance (Ω · cm) 0.40 0.45 0.31 0.45

As shown in Tables 1 and 2, it can be seen that in Example 1-5, the flexural modulus was 25 GPa or more, the EMI shielding effect was 40 dB or more, and the surface resistance was 3.0 Ω or less.

In contrast, Comparative Example 1, in which the second metal filler was not applied, and Comparative Example 2, in which the first metal filler was not applied, showed a decrease in electrical conductivity. In Comparative Example 3 in which the surface-treated carbon fiber was sieved with a urethane resin rather than a polyamide or an epoxy resin, the flexural modulus was lowered. On the other hand, Comparative Example 4 in which the melting point difference between the thermoplastic resin (A) and the first metal filler (B) was less than 30 degrees showed poor electrical conductivity.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood that the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the embodiments described above are in all respects illustrative and not restrictive.

10: first metal filler 20: second metal filler
30: surface-treated carbon fiber 40: thermoplastic resin

Claims (10)

(A) a thermoplastic resin;
(B) a first metal filler;
(C) a second metal filler; And
(D) surface-treated carbon fibers;
And,
The surface-treated carbon fiber (D) is surface-treated with a resin or a metal, the surface-treated resin is a polyamide or an epoxy resin,
Wherein a melting point of the thermoplastic resin (A), the first metal filler (B), and the second metal filler (C) satisfy the following formula (1):
[Formula 1]
Tma -30 ° C> Tmb , Tma + 500 ° C < Tmc
(Tmc is the melting point (占 폚) of the second metal filler (C)). The melting point (占 폚) of the thermoplastic resin (A), Tmb is the melting point (占 폚) of the first metal filler (B)
The high rigidity electromagnetic wave shielding composite material according to claim 1, wherein the thermoplastic resin (A) is a crystalline thermoplastic resin.
The high rigidity electromagnetic wave shielding composite material according to claim 1, wherein the second metal filler (C) is spherical, branched or flaky.
The high rigidity electromagnetic wave shielding composite material according to claim 1, wherein the weight ratio of the first metal filler (B) and the second metal filler (C) is 1: 1 to 3: 1.
The highly rigid electromagnetic wave shielding composite material according to claim 1, wherein the surface-treated carbon fiber (D) has a diameter of 3 to 10 탆.
The method according to claim 1, wherein the surface-treated metal fibers on the surface-treated carbon fibers (D) comprise at least one metal selected from the group consisting of aluminum, stainless steel, iron, chromium, nickel, black nickel, copper, silver, High Rigidity Electromagnetic Wave Shielding Composite.
The composite material of claim 1, wherein the composite material comprises (A) 10 to 84% by weight of a thermoplastic resin; (B) 5 to 35% by weight of a first metal filler; (C) 0.5 to 30% by weight of a second metal filler; And (D) 10 to 60% by weight of surface-treated carbon fibers.
The high strength electromagnetic wave shielding composite material according to claim 1, wherein the content of the surface-treated carbon fibers (D) is larger than the content of the thermoplastic resin (A).
The composite material according to claim 1, wherein the composite material further comprises at least one additive selected from the group consisting of a flame retardant, an impact modifier, a plasticizer, a coupling agent, a heat stabilizer, a light stabilizer, an inorganic filler, a releasing agent, a dispersant, High strength electromagnetic wave shielding composite material.
The thermoplastic resin forms a continuous phase,
Wherein the first metal filler, the second metal filler, and the surface-treated carbon fibers form a dispersed phase on the continuous phase,
Wherein the melting point of the first metal filler is lower than the melting point of the second metal filler by 700 DEG C or more and the first metal filler is continuously or discontinuously surrounded on the surface of the second metal filler,
High rigidity electromagnetic shielding composite having a flexural modulus of 25 GPa or more at a thickness of 3.2 mm according to ASTM D790, an EMI shielding of at least 40 dB at 1 GHz according to ASTM D257, and a surface resistance of 3.0 Ω or less.

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