KR20170025599A - Resin composition for electromagnetic interference shielding and article using the same - Google Patents

Abstract

The present invention relates to a resin composition for shielding electromagnetic wave, and to a molded article using the same. According to the present invention, the resin composition comprises: a polyamide resin; a conductive elastomer whose conductivity ranges from 110^6 to 110^10 /sq; and a carbon fiber.

Description

Technical Field [0001] The present invention relates to a resin composition for shielding electromagnetic waves and a molded article using the resin composition.

The present invention relates to a resin composition for shielding electromagnetic waves and a molded article using the same. Specifically, the present invention relates to a resin composition for shielding a polyamide-based electromagnetic wave shielding material having excellent processability and electromagnetic wave shielding performance, including a conductive elastomer, and a molded article using the same.

Electromagnetic waves are known to cause harmful effects on the human body as well as cause malfunctions in surrounding parts or devices due to noise caused by electrostatic discharge. Recently, electric and electronic products are becoming multifunctional and miniaturized. As the information and communication devices are developed, the electromagnetic wave use band is gradually shifting to a high frequency band, and electromagnetic wave pollution in everyday life is rapidly increasing. As a result, electromagnetic regulations are being strengthened in developed countries and domestic countries, and development of electromagnetic shielding technology to prevent exposure to electromagnetic waves is becoming more important.

Conventionally, a method of using a metal material having high conductivity has been used as a method for shielding electromagnetic waves. However, there is a problem that the metal material is difficult to process in a complicated pattern and is heavy. Generally, it is produced by die casting method, and the production cost is high and the defect rate is high.

As a result, a technique has been developed in which a conductive plastic such as carbon fiber is mixed with a thermoplastic resin that is easy to mold and has excellent economy compared with a metal material and is used as a resin for shielding electromagnetic waves. However, the electromagnetic shielding resin developed to date has a lower electromagnetic wave shielding performance than metal materials and has a limitation in application to electronic devices. In order to improve electromagnetic shielding performance, it is necessary to add an excess amount of carbon fiber or add a metal filler or the like. In this case, as the carbon fiber or metal filler is mixed in a large amount, not only the workability is deteriorated, It is not possible to reach the required level.

Therefore, it is necessary to develop a resin for electromagnetic wave shielding which is excellent in both workability and electromagnetic wave shielding performance.

A related prior art is Korean Patent Publication No. 2012-0034538.

It is an object of the present invention to provide a resin composition for electromagnetic shielding which is excellent in both workability and electromagnetic wave shielding performance.

Another object of the present invention is to provide a molded article produced using the resin composition for shielding electromagnetic waves.

In one aspect, the present invention provides a resin composition for shielding electromagnetic interference comprising a polyamide resin, a conductive elastomer having an electrical conductivity of 1 x 10 ⁶ ? / Sq to 1 x 10 ¹⁰ ? / Sq, and a carbon fiber.

The polyamide resin and the conductive elastomer are preferably mixed in a weight ratio of 1: 1 to 10: 1.

The polyamide resin may have an intrinsic viscosity (IV) of 0.6 dL / g to 1.5 dL / g as measured with a Ubbelodhde viscometer in a sulfuric acid solution at 25 ° C.

The polyamide resin may be contained in an amount of 20% by weight to 70% by weight based on 100% by weight of the total amount of the resin composition.

The conductive elastomer may be a polyamide block copolymer, and preferably, it may include a hydrophilic polyether segment and an amide segment.

The conductive elastomer may be contained in an amount of 10% by weight to 60% by weight based on 100% by weight of the total amount of the resin composition.

The carbon fibers may be contained in an amount of 20 wt% to 65 wt% based on 100 wt% of the total resin composition.

The polyamide resin and the conductive elastomer may form a three-dimensional ionic dissipative network structure.

In another aspect, the present invention provides a molded article produced using the resin composition for electromagnetic shielding according to the present invention.

The surface resistance of the molded article may be 1 to 20? 占 cm m and the electromagnetic wave shielding ratio may be 20 dB or more.

Further, the molded article may have a change amount of the electromagnetic wave shielding ratio of 10 dB or more and a change amount of the surface resistance of 10 Ω · cm or less when compared with a molded article made of a resin composition having the same carbon fiber content and no conductive elastomer .

INDUSTRIAL APPLICABILITY The resin composition for shielding electromagnetic interference according to the present invention makes it possible to realize excellent electrical conductivity and electromagnetic shielding performance without decreasing workability by using a conductive elastomer without increasing the content of carbon fiber or metal filler.

Fig. 1 is a graph showing the electromagnetic wave shielding performance of Examples 1 and 2 and Comparative Example 1. Fig.
2 is a graph showing the electromagnetic wave shielding performance of Examples 3 to 5 and Comparative Example 2;

Hereinafter, the present invention will be described more specifically.

Resin composition

First, the resin composition for electromagnetic shielding according to the present invention will be described.

(A) a polyamide resin, (B) a conductive elastomer having an electric conductivity of 1 10 ⁶ ? / Sq to 1 10 ¹⁰ ? / Sq, and (C) a conductive elastomer, Carbon fiber.

(A) a polyamide resin

As the polyamide resin to be used in the present invention, various polyamide resins known in the art, for example, an aromatic polyamide resin, an aliphatic polyamide resin, or a mixture thereof may be used, and there is no particular limitation.

The aromatic polyamide resin is a polyamide having an aromatic group in its main chain, and may be a wholly aromatic polyamide, a semi-aromatic polyamide or a mixture thereof.

The wholly aromatic polyamide means a polymer of an aromatic diamine and an aromatic dicarboxylic acid, and a semiaromatic polyamide means that at least one aromatic unit and a non-aromatic unit are contained between amide bonds. For example, the semiaromatic polyamide may be a polymer of an aromatic diamine and an aliphatic dicarboxylic acid, or a polymer of an aliphatic diamine and an aromatic dicarboxylic acid.

On the other hand, the aliphatic polyamide means a polymer of an aliphatic diamine and an aliphatic dicarboxylic acid.

Examples of the aromatic diamine include, but are not limited to, p-xylylenediamine, m-xylylenediamine, and the like. These may be used alone or in combination of two or more.

Examples of the aromatic dicarboxylic acid include phthalic acid, isophthalic acid, terephthalic acid, naphthalene-2,6-dicarboxylic acid, diphenyl-4,4'-dicarboxylic acid and 1,3-phenylene dioxydiacetic acid. But is not limited thereto. These may be used alone or in combination of two or more.

Examples of the aliphatic diamine include, but are not limited to, 1,2-ethylenediamine, 1,3-propylenediamine, 1,6-hexamethylenediamine, 1,12-dodecylenediamine and piperazine . These may be used alone or in combination of two or more.

Examples of the aliphatic dicarboxylic acid include adipic acid, sebacic acid, succinic acid, glutaric acid, azelaic acid, dodecanedioic acid, dimeric acid, and cyclohexanedicarboxylic acid. no. These may be used alone or in combination of two or more.

Preferably, an aliphatic polyamide resin can be used as the polyamide resin, and more preferably, a polyamide 66 containing a repeating unit represented by the following formula (1) can be used. When an aliphatic polyamide resin is used as the polyamide resin, compatibility with the conductive elastomer during blending is excellent, and even when the content of the carbon fiber is high, excellent workability can be exhibited.

[Chemical Formula 1]

- (NH- (CH ₂ ) ₆ -HN-CO- (CH ₂ ) ₄ -CO) _n-

In Formula 1, n is 200 to 15,000.

Meanwhile, the polyamide resin used in the present invention has an intrinsic viscosity (IV) of 0.6 dL / g to 1.5 dL / g, preferably 0.7 dL / g, as measured with a Ubbelodhde viscometer in a sulfuric acid solution at 25 ° C / g to 1.3 dL / g, more preferably 0.8 dL / g to 1.2 dL / g. When the viscosity of the polyamide resin satisfies the above-described numerical range, it is advantageous to form a three-dimensional ionic dissipative network structure of the conductive elastomer in the polyamide resin.

On the other hand, the polyamide resin may contain 20% by weight to 70% by weight, preferably 20% by weight to 50% by weight, based on 100% by weight of the total amount of the resin composition comprising (A) + (B) Preferably from 25% by weight to 50% by weight. When the content of the polyamide resin satisfies the above numerical range, a composition having both excellent processability and electromagnetic shielding performance can be obtained.

(B) Conductive elastomer

The conductive elastomer used in the present invention is to improve the electrical conductivity of the resin composition and has an electrical conductivity of 1 x 10 ⁶ ? / Sq to 1 x 10 ¹⁰ ? / Sq, preferably 1 x 10 ⁶ ? / Sq to 1 × 10 ⁹ Ω / sq. The conductive elastomer is not particularly limited as long as its electrical conductivity satisfies the above range. For example, the conductive elastomer may be a conductive material such as an ionic liquid or an elastomer containing an ionic functional group.

According to an embodiment, the conductive elastomer may be a polyamide-based block copolymer, and preferably a polyamide-based block copolymer including a hydrophilic polyether segment and an amide segment. When such a polyamide-based block copolymer is used as the conductive elastomer, compatibility with the polyamide resin (A) is excellent and it is more advantageous in improving workability and electromagnetic shielding performance.

Examples of commercially available conductive elastomers include, but are not limited to, PEBAX MH-2030 and EBAX-2080 available from Akima.

When the conductive elastomer and the polyamide resin are blended, the conductive elastomer and the polyamide resin form a three-dimensional ionic dissipative network structure while forming a co-continuous phase. Thereby improving the electromagnetic shielding performance of the resin composition as a whole. Further, since the conductive elastomer is flexible, unlike the case where the content of the metal filler or the carbon fiber is increased, the workability is not deteriorated. The conductive elastomer may be used in an amount of 10 to 60% by weight, preferably 10 to 50% by weight, based on 100% by weight of the total of the resin composition comprising (A) + (B) More preferably from 10% by weight to 40% by weight. When the content of the conductive elastomer satisfies the above-described numerical range, a composition excellent in both workability and electromagnetic shielding performance can be obtained.

Meanwhile, in the resin composition of the present invention, the polyamide resin (A) and the conductive elastomer (B) may be mixed in a weight ratio of 1: 1 to 10: 1. Preferably, the weight ratio of the polyamide resin (A): conductive elastomer (B) may be 1: 1 to 9: 1, more preferably 1: 1 to 8: 1. When the weight ratio of the polyamide resin (A) to the conductive elastomer (B) satisfies the above-described numerical value range, the electromagnetic wave shielding performance improving effect is more excellent.

(C) carbon fiber

The carbon fiber used in the present invention is well known to those skilled in the art and is commercially available and can be prepared by a conventional method.

For example, the carbon fibers may be prepared from a PAN system or a pitch system.

The average diameter of the carbon fibers is not limited thereto, but may be, for example, 1 to 30 占 퐉, preferably 3 to 20 占 퐉, more preferably 5 to 15 占 퐉. When the average diameter of the carbon fibers satisfies the above range, excellent physical properties and electrical conductivity can be obtained.

The carbon fibers may be subjected to a surface treatment. For example, those surface-treated with urethane may be used.

The carbon fibers may be bundled. For example, the carbon fiber may be a long carbon fiber bundle of 400 to 3000 TEX, preferably a carbon fiber having a bundle shape of 800 to 2400 TEX, more preferably 800 to 1700 TEX. When the carbon fiber satisfies the above range, it is advantageous that the impregnation is easy.

As described above, the bundle-shaped carbon fiber is impregnated with the melt of the polyamide resin (A), and the polyamide resin (A) is applied to the surface thereof. The carbon fiber is then cut into a length of 8 to 20 mm in a pelletizing process, 20 mm pellets. The length of the pellet is equal to the length of the cut carbon fiber since it is cut along the length of the carbon fiber.

The pellets thus produced can be formed into a molded product through a molding process such as injection molding, and the final molded product has a structure in which carbon fibers are dispersed to each other.

In addition, when a long carbon fiber having a length of 8 to 20 mm is applied as described above, the length of the residual fiber is generally 0.5 to 6 mm in a molded article. Here, the length of the residual fiber refers to the fiber length after pelletization and subsequent molding. The molding process is a typical molding condition. For example, the molding step may be performed under an injection condition of, for example, 280 to 320 DEG C and a pressure of 170 MPa to 190 MPa, but is not limited thereto.

The carbon fibers may be used in an amount of 20% by weight to 65% by weight, preferably 20% by weight to 50% by weight, based on 100% by weight of the total resin composition comprising (A) + (B) . The resin composition of the present invention contains a conductive elastomer and can realize excellent electromagnetic wave shielding performance even when only a relatively small amount of carbon fiber is used.

The composition of the present invention may further contain additives such as a flame retardant, a plasticizer, a coupling agent, a heat stabilizer, a light stabilizer, an inorganic filler, a releasing agent, a dispersant, a dripping inhibitor, a weather stabilizer, . These additives may be used alone or in combination of two or more. At this time, various carbon fillers other than the carbon fibers (C) may be used as the carbon filler. For example, graphite, carbon nanotubes, carbon black or metal coatings thereof may be used.

The composition of the present invention may be prepared in the form of a pellet by mixing the above components through a Henschel mixer, a V blender, a tumbler blender, a ribbon blender, or the like, and melt-extruding the mixture. At this time, the melt extrusion is performed by using a single screw extruder or a twin screw extruder 240 to 320. < / RTI >

Molded product

The molded article according to the present invention is produced from the resin composition of the present invention. For example, the molded article may be prepared by mixing a resin composition comprising (A) a polyamide resin, (B) a conductive elastomer, and (C) a carbon fiber, and melt-extruding the mixture into a pellet, Molding, casting, or the like.

The molded article of the present invention produced as described above has the same level of carbon fibers as the molded article produced by the resin composition containing no conductive elastomer, great.

Specifically, the molded article of the present invention has a surface resistance of 1 to 20? 占 cm m, preferably 1 to 15? 占, m, more preferably 1 to 10? 占 cm m, and an electromagnetic wave shielding rate of 20 dB or more, 90dB, and more preferably 20dB to 70dB. More specifically, when the molded article of the present invention has the same content of carbon fiber and a molded article made of a resin composition containing no conductive elastomer, when the change amount of the electromagnetic wave shielding rate is 10 dB or more and the change amount of the surface resistance is 10? 占 cm m or less.

At this time, the electromagnetic wave shielding ratio is a value measured at 1 GHz according to ASTM D4935-10, and the surface resistance is measured by a 4 point probe method using a Loresta-GP device manufactured by Mitsubishi Chemical.

The amount of change in the electromagnetic wave shielding rate means a value obtained by subtracting the electromagnetic wave shielding ratio produced by the resin composition not containing the conductive elastomer from the electromagnetic wave shielding factor of the molded article made of the resin composition of the present invention, The amount of change in the surface resistance means the difference in the surface resistance value of the molded article made of the resin composition having the same surface resistance value and carbon fiber content of the molded article made of the resin composition of the present invention and not containing the conductive elastomer.

As described above, the molded article manufactured using the resin composition according to the present invention is excellent in electromagnetic wave shielding performance and can be usefully used in various electronic products such as mobile phones and TVs

Hereinafter, the present invention will be described in more detail with reference to preferred embodiments. However, the following examples are intended to illustrate one example of the present invention, and the present invention is not limited to the following examples.

Example

The specifications of each component used in the following examples and comparative examples are as follows

(A) Polyamide resin: PA66 (IV 1.0 dL / g) of Adachi Co. was used.

(B) Conductive elastomer

(b1) PEBAX MH-2030 manufactured by Arkema Co., Ltd. having an electric conductivity of 1 × 10 ⁷ to 9 × 10 ⁷ Ω / sq was used.

(b2) MV-2080 manufactured by Arkema Co., Ltd. having an electric conductivity of 1 × 10 ⁷ to 9 × 10 ⁷ Ω / sq was used.

(C) carbon fiber

(c1) PANEX-35 from Zoltek was used.

(c2) SGL Carbon Fiber SIGAFIL C PUT.

Example  1 to 7 and Comparative Example  One

Each component was extruded in a biaxial extruder having L / D = 35 and? = 45 mm in the contents shown in the following Table 1, and then molded into pellets. The prepared pellets were injected at 300 to prepare specimens having a thickness of 2.1T and 6 (inch) x 6 (inch). Electromagnetic wave shielding performance and surface resistance were measured according to the following methods. The measurement results are shown in Table 1 below.

How to measure property

(1) Electromagnetic wave shielding performance (dB): The electromagnetic wave shielding efficiency at 1 GHz was measured according to ASTM D4935-10.

(2) Surface resistance (Ω · cm): Measured by a 4 point probe method using a Loresta-GP apparatus manufactured by Mitsubishi Chemical Co.

division Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Comparative Example 1 Comparative Example 2 Furtherance
(weight%) (A) 50 35 45 35 25 50 35 70 50 (B) (b1) 20 35 5 15 25 - - - - (b2) - - - - - 20 35 - - (C) (c1) 30 30 - - - 30 30 30 - (c2) - - 50 50 50 - - - 50 Properties Surface resistance E0 E0 E1 E1 E1 E0 E0 E0 E1 Electromagnetic wave shielding
(1 GHz) 58 68 25 25 30 50 58 56 15

As shown in Table 1, the resin compositions of Examples 1 to 7 using the conductive elastomer had better electromagnetic shielding performance and surface resistances than Comparative Examples 1 and 2 containing the same amount of carbon fibers .

FIG. 1 is a graph showing electromagnetic wave shielding performance according to electromagnetic wave frequency bands of a test piece manufactured according to Comparative Example 1 and Examples 1 and 2. FIG. 2 is a graph showing the electromagnetic wave shielding performance according to Comparative Example 2 and Examples 3 and 5 A graph showing the electromagnetic wave shielding performance according to the electromagnetic wave frequency band of the manufactured specimen is shown. 1 and 2, it can be seen that the specimens of the examples according to the present invention have excellent electromagnetic wave shielding performance in the entire frequency band as compared with the specimens of the comparative example having the same carbon content.

Claims (11)

Polyamide resins;
A conductive elastomer having an electric conductivity of 1 x 10 ⁶ ? / Sq to 1 x 10 ¹⁰ ? / Sq; And
A resin composition for shielding electromagnetic interference comprising carbon fibers. The method according to claim 1,
Wherein the polyamide resin and the conductive elastomer are mixed in a weight ratio of 1: 1 to 10: 1. The method according to claim 1,
Wherein the polyamide resin has an intrinsic viscosity (IV) of 0.6 dL / g to 1.5 dL / g, as measured with a Ubbelodhde viscometer in a sulfuric acid solution at 25 캜. The method according to claim 1,
20% to 70% by weight of the polyamide resin;
10% to 60% by weight of the conductive elastomer; And
And 20 to 65 wt% of the carbon fibers. The method according to claim 1,
Wherein the conductive elastomer is a polyamide-based block copolymer. 6. The method of claim 5,
Wherein the conductive elastomer comprises a hydrophilic polyether segment and an amide segment. The method according to claim 1,
Wherein the polyamide resin and the conductive elastomer form a three-dimensional ionic dissipative network structure. A molded article produced by using the resin composition for electromagnetic shielding according to any one of claims 1 to 7. 9. The method of claim 8,
The molded article has a surface resistance of 1 to 20? 占 cm m. In the eighth aspect,
The molded article has a shielding rate of 20 dB or more against 100 MHz electromagnetic waves measured according to ASTM D4935-10. 9. The method of claim 8,
Wherein the molded product has a change amount of the electromagnetic wave shielding rate of 10 dB or more and a change amount of the surface resistance of 10 Ω · cm or less when compared with a molded product made of a resin composition having the same carbon fiber content and not containing a conductive elastomer.

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