KR20110079103A - Thermoplastic resin composition with good electromagnetic wave shielding - Google Patents

Abstract

PURPOSE: A thermoplastic resin composition is provided to ensure high modulus, high stiffness, high strength, and excellent electromagnetic wave shielding property by comprising a thermoplastic resin, inorganic filler, and metal. CONSTITUTION: A thermoplastic resin composition with excellent electromagnetic wave shielding property comprises 20~50 weight% of a thermoplastic resin, 5~80 weight% of inorganic filler, and 5~50 weight% of metal with a low melting point of 300°C or less. The thermoplastic resin is selected from the group consisting of polyamide, polyethyleneterephthalate, polybutyleneterephthalate, polyacetal, polycarbonate, polyimide, polyphenyleneoxide, polysulfone, polyphenylenesulfide, polyamide-imide, polyethesulfone, liquid crystal polymer, polyetherketone, polyetherimide, polyolefin, acrylonitrile-butadiene-styrene, polystyrene, syndiotactic polystyrene, and mixture thereof.

Description

Thermoplastic Resin Composition with good Electromagnetic wave shielding

The present invention relates to a thermoplastic resin composition, and more particularly, to a thermoplastic resin composition having high modulus and high performance electromagnetic interference (EMI) shielding properties.

The thermoplastic resin refers to a plastic that softens when heated, exhibits plasticity, and solidifies when cooled. Such thermoplastic resins include general-purpose plastics such as polyethylene resins, polypropylene resins, acrylic resins, styrene resins or vinyl resins, and engineering such as polycarbonate resins, polyphenylene ether resins, polyamide resins, polyester resins or polyimide resins. It can be divided into plastics.

The thermoplastic resin is excellent in workability and moldability, and is widely applied to various household products, office automation equipment, electrical and electronic products, and the like. Moreover, according to the kind and the characteristic of the product in which such a thermoplastic resin is used, in addition to the said excellent workability and moldability, the attempt to add a special property to a thermoplastic resin and to use it as a high value-added material is continuously made. Among these, many attempts have been made to provide a thermoplastic resin for shielding electromagnetic waves by imparting electromagnetic shielding performance to the thermoplastic resin, and to use it for automobiles, various electric devices, electronic assemblies, cables, and the like.

Such an electromagnetic shielding thermoplastic resin is typically manufactured using an electromagnetic shielding thermoplastic resin composition in which additives such as metal powder, metal coated inorganic powder or metal fiber are mixed with the thermoplastic resin. However, since the additive has a high specific gravity, the electromagnetic shielding performance of the thermoplastic resin for electromagnetic shielding is not sufficient unless a considerable amount is added. In addition, when the amount of the additive is added to improve the electromagnetic wave shielding performance, the properties of the thermoplastic resin itself, for example, impact resistance, etc. are lowered, making it difficult to use the thermoplastic resin for electromagnetic wave shielding.

An object of the present invention is to provide a thermoplastic resin composition having high modulus, high performance electromagnetic interference shielding properties.

Another object of the present invention is to provide a molded article prepared from the thermoplastic resin composition described above.

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

In order to solve the above technical problem, the present invention comprises (A) 20 to 50% by weight of the thermoplastic resin (B) 5 to 80% by weight of the inorganic filler and (C) 5 to 50% by weight of the metal having a low melting point of 300 ℃ or less Provided is a thermoplastic resin composition.

In one embodiment of the invention, the (B) inorganic filler is a glass fiber and carbon fiber is mixed.

In another embodiment of the present invention, the (B) inorganic filler is a glass fiber: carbon fiber is mixed in a weight ratio of 99: 1 ~ 5:95.

In another embodiment of the present invention, the metal of (C) low melting point 300 ℃ or less is bismuth (Bi), cadmium (Cd), gallium (Ga), indium (In), lead (Pb), tin (Sn) and It is an alloy consisting of two or more.

In another embodiment of the present invention, the (C) low melting point 300 ℃ or less in the metal further comprises copper (Cu), aluminum (Al), nickel (Ni), silver (Ag) and two or more alloys.

In another embodiment of the present invention, the metal (C) having a low melting point of less than 300 ℃ is Sn-Cu, Sn-Ag, Sn-Ag-Cu, Sn-Ag-Cu-Bi alloy.

In another embodiment of the present invention, it further comprises one or more additives selected from the group consisting of heat stabilizers, mold release agents, dispersants, anti-drip agents, weather stabilizers, inorganic fillers and inorganic fibers.

In order to achieve the above another technical problem, the present invention provides a thermoplastic resin composition characterized in that the bending modulus is 15 to 40 GPa, and the electromagnetic shielding value is 20 to 80 dB (1 GHz).

In order to achieve the above another technical problem, the present invention provides a molded article characterized in that the bending modulus produced from the thermoplastic resin composition is 15 to 40 GPa, and the electromagnetic shielding value is 20 to 80 dB.

The present invention provides a thermoplastic resin composition having the effect of high modulus, high stiffness, and high performance electromagnetic interference shielding properties.

Hereinafter, specific contents of the present invention will be described in detail below.

The present invention provides a thermoplastic resin composition comprising (A) 20 to 50% by weight of thermoplastic resin and (B) inorganic filler 5 to 80% by weight (C) 5 to 50% by weight of metal having a low melting point of 300 ° C. or less.

(A) thermoplastic resin

Specific examples of the thermoplastic resin of the present invention include polyamide; Polyalkylene terephthalates such as polyethylene terephthalate or polybutylene terephthalate; Polyacetals; Polycarbonate; Polyimide; Polyphenylene oxide; Polysulfones; Polyphenyl rensulphides; Polyamide imide; Polyether sulfones; Liquid crystal polymer; Polyether ketones; Polyetherimide; Polyolefins such as polypropylene or polyethylene; Acrylonitrile-butadiene-styrene; polystyrene; Syndiotactic polystyrene; Etc. can be mentioned. It is also possible to use those selected from the group consisting of these blends and combinations thereof.

Preferably, the thermoplastic resin (A) of the present invention is a crystalline thermoplastic resin. Such a crystalline thermoplastic resin has an advantage of forming a conductive pass better than an amorphous resin due to its property of rejecting fillers (other components other than the component (A) in the resin composition of the present invention) out of the crystal region during its crystallization. . In addition, in terms of mechanical rigidity, the reinforcing effect of the filler is much better than that of the amorphous resin.

The crystalline thermoplastic resin is preferably a group consisting of polyamide, polyethylene terephthalate, polybutylene terephthalate, polyacetal, polyphenylene sulfide, liquid crystal polymer, polyetherketone, polyolefin, syndiotactic polystyrene, and mixtures thereof. Can be selected from.

In the thermoplastic resin composition of the present invention, the content of the (A) thermoplastic resin is preferably 20 to 50% by weight, more preferably 15 to 35% by weight. When the content of the thermoplastic resin is less than 20% by weight, it is difficult to process the resin composition, and when the content of the thermoplastic resin is more than 50% by weight, it is difficult to realize the target physical properties of the present invention.

(B) inorganic filler

Inorganic fillers used in the present invention include glass fiber, carbon fiber, alumina fiber, aramid fiber, silicon carbide fiber, ceramic fiber, boron fiber, calcium carbonate, asbestos, titanium dioxide, silicate, alumina, aluminum hydroxide, talc, silica, Mica, clay, mica, glass powder, glass beads, barium sulfate, whiskers and the like can be used, but are not necessarily limited thereto. These can be used individually or in mixture of 2 or more types.

The inorganic filler may be coated with a surface treatment agent such as a coupling agent, it may be added as it is without coating.

In this invention, it is preferable to mix and use glass fiber and carbon fiber. Thus, mixed use is more excellent in modulus and electromagnetic wave shielding.

In the present invention, more preferably, glass fibers and carbon fibers are used in a range of 99: 1 to 5:95, preferably 63:37 to 25:75 Pa weight ratio. If the weight ratio of the glass fiber to the carbon fiber is less than 99: 1 mm, it may cause problems in that the processability is difficult, the composition is brittle, EMI shielding is reduced, and bending strength is reduced. When the weight ratio of glass fiber to carbon fiber exceeds 5:95, EMI shielding property is reduced and flexural strength is reduced.

The glass fiber of the present invention is used for the purpose of improving the strength while at the same time canceling the fracture characteristics of the composition generated when using only carbon fiber can be used conventional glass fiber, preferably to reinforce the physical properties High rigid glass fibers used for the purpose can be used. It is possible to use circular, elliptical, square, rectangular and amorphous glass fibers in cross section, preferably glass fibers having a rectangular cross section. If the cross section is square or rectangular, the length of one side is preferably 5 to 50 μm, the fiber length is 1 to 15 mm, and if the cross section is round or oval, glass fibers having an average diameter of 5 to 30 μm and a fiber length of 1 to 15 mm are preferably used. Can be.

Glass fiber used in the present invention is well known to those skilled in the art, it is easy to purchase commercially, it can be produced by conventional methods.

The carbon fiber of the present invention is mainly responsible for the electrical conductivity and high rigidity of the composition. The carbon fiber of the present invention may be selected from the group classified into conventional carbon fibers of the PAN series or the Pitch series. More specifically, carbon fibers having an average diameter of 1 to 15 µm and a fiber length of 3 to 12 mm in cross section can be preferably used.

The inorganic filler used in the present invention may be included in 5 to 80% by weight, preferably 40 to 80% by weight, more preferably 50 to 75% by weight. 　 When the inorganic filler according to the present invention is included in an amount of 5 to 80% by weight, it exhibits excellent modulus, and at the same time, has a characteristic of ensuring electromagnetic shielding effect. On the other hand, when the inorganic filler is included in less than 5% by weight, the reinforcing effect of the inorganic filler disappears, so that the heat resistance and whiteness are greatly reduced.When the inorganic filler is included in an amount of more than 80% by weight, the injection pressure and injection speed are increased due to the large drop in fluidity during injection. As a result, there is a concern that the smoothness of the surface of the specimen is lowered and the luminance is lowered due to gas generation.

(C) low melting point metal alloy (LMA)

The low melting point metal is a metal which is melted at a temperature significantly lower than the melting point of a general metal, and may be used as long as the product melts to some extent at the melting temperature of the mother resin. If the melting point of the low melting point metal is too high, it cannot be used because it is a solid state such as lump when processing with the resin. If the melting point of the low melting point metal is too low, there is a problem in kneading with the resin because the metal becomes a liquid such as water. do. Therefore, a careful approach considering the processing temperature range is required. In the present invention, the low melting point metal may be a metal or alloy having a melting point of 300 ° C. or less, and preferably a metal or alloy having a melting point of 250 ° C. to 300 ° C. may be used.

The metal having a low melting point of 300 ° C. or less, which is a component of the thermoplastic resin composition of the present invention, is composed of bismuth (Bi), cadmium (Cd), gallium (Ga), indium (In), lead (Pb), tin (Sn), and two or more thereof. Alloys can be used. Additionally, copper (Cu), aluminum (Al), nickel (Ni), silver (Ag), and two or more metals may be used by alloying with a metal having a low melting point of 300 ° C. or less. More preferably, Sn-Cu, Sn-Ag, Sn-Ag-Cu, Sn-Ag-Cu-Bi alloy can be used.

In the resin composition of the present invention, a metal having a low melting point of 300 ° C. or less may be used in an amount of 5 to 50 wt%, and preferably 5 to 30 wt%. If the content of the metal is less than 5% by weight, there is a drawback of insufficient EMI shielding properties. If the content of the metal is more than 50% by weight, the viscosity and specific gravity of the composition are adversely affected.

The thermoplastic resin composition of the present invention can satisfy high modulus, high performance electromagnetic wave interference shielding properties at the same time, and preferably, the thermoplastic resin (A), the inorganic filler (B), and the metal having a low melting point of 300 ° C. or less ( C) By adjusting the content between the components can satisfy the performance of the flexural modulus 15 ~ 40 GPa measured according to ASTM D790, electromagnetic shielding 20 ~ 80 dB (1 GHz) measured according to ASTM D4935.

In addition, the thermoplastic resin composition of the present invention may further contain an additive depending on the intended use or effect, in addition to the four main components described above. For example, thermal stabilizers, mold release agents, dispersants, anti-drip agents, weather stabilizers, nucleating agents, antistatic agents, stabilizers, reinforcing agents, pigments, or dyes may be further included. The types of additives that can be used are apparent to those skilled in the art, and may be included in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the thermoplastic resin composition.

The thermoplastic resin composition of the present invention can be produced by a known method for producing a conventional thermoplastic resin composition. For example, each of the above-mentioned components and other additives may be mixed at the same time, and then melt-extruded in an extruder to prepare pellets.

Another aspect of the present invention provides a molded article prepared from the thermoplastic resin composition of the present invention. The molded article of the present invention can be usefully applied to a variety of products, such as metal inside the mobile phone, bracket meta-materials, electronics inner frame, home appliance exterior materials that require high rigidity, high strength, high performance electromagnetic interference shielding.

In a specific example of the present invention, the plastic molded article according to the present invention may have a flexural modulus measured according to ASTM D790 of 15 to 40 GPa, and an electromagnetic shielding value measured according to ASTM D4935 of 20 to 80 dB (1 GHz). have.

The present invention will be further illustrated by the following examples, which are merely illustrative of the present invention and are not intended to limit or limit the scope of the present invention.

Example

Specifications of the thermoplastic resin, the inorganic filler, and the low melting point metal used in the following Examples and Comparative Examples are as follows.

(A) thermoplastic resin

As the thermoplastic resin used in the present invention, nylon 6 (Nylon 6) 1011 BRT (trade name) of Hyosung was used.

(B) inorganic filler

(B1) glass fiber

The glass fiber used in the present invention was CSG 3PA-820 (trade name) having a rectangular cross section (a = 28 μm, b = 7 μm) of Nittobo, Japan, with an average length of 3 mm.

(B2) carbon fiber

The carbon fiber used in the present invention used an average length of 6 mm from Toho Tenax, TENAX A HT C493 (trade name) of Pan series.

(C) low melting point 300 ℃ or less metal

(C1) The metal having a low melting point of 300 ° C. or less used in the present invention was 97C (trade name), a powder type tin-copper alloy manufactured by Warton Metals Limited.

(C2) Nickel-iron alloys Permalloy (Dongbu Fine Chemical Co., Ltd.) were used.

Examples 1-7 and Comparative Examples 1-3

Each component was mixed in a conventional mixer in the content ratio as shown in Table 1 below and extruded using a twin screw extruder having L / D = 35 and Φ = 45 mm, and then the extrudate was prepared in pellet form, followed by injection. Specimens for physical property measurement and flame retardancy evaluation at a temperature of 280 ° C. were prepared using a 10 oz injection machine. These specimens were measured for 48 hours at 23 ° C. and 50% relative humidity, and then measured for physical properties according to ASTM standards.

Modulus evaluated Flexural Modulus (FM) according to ASTM D790 specification.

Electromagnetic shielding rate (EMI) was measured at a specimen thickness of 2T according to EMI ASTM D790.

Table 1 shows the results of the physical properties measured as described above.

A B1 B2 C1 C2 FM (GPa) EMI (dB)
(1 GHz) Example 1 30 20 40 10 28 40 Example 2 30 30 30 10 27 38 Example 3 30 35 25 10 26 36 Example 4 30 30 25 15 25 40 Example 5 30 25 30 15 24 43 Example 6 25 30 35 10 27 38 Example 7 25 25 35 15 28 44 Comparative Example 1 25 75 28 One Comparative Example 2 30 70 24 2 Comparative Example 3 30 20 40 10 26 28

(Unit: wt%)

As shown in Table 1, in Examples 1 and 2, the higher the content of carbon fiber, the higher the modulus, the more effective for electromagnetic shielding, and the higher the melting point metal in Examples 3 and 4, the more effective for electromagnetic shielding Can be.

In Comparative Examples 1 and 2 it can be seen that there is almost no electromagnetic shielding effect when using only glass fibers without using a low melting point metal. In Comparative Example 3, nickel-iron alloys such as Permalloy have a bending strength and an electromagnetic shielding effect, but the electromagnetic shielding of the low melting point of the present invention is less than 300 ℃ metal.

Simple modifications and variations of the present invention can be readily used by those skilled in the art, and all such variations or modifications are considered to be included within the scope of the present invention.

Claims (17)

(A) thermoplastic resin; (B) inorganic fillers; And (C) low melting point 300 ℃ or less metal Thermoplastic resin composition excellent in electromagnetic wave shielding properties, including. The electromagnetic wave shielding property of claim 1, further comprising 20 to 50 wt% of the thermoplastic resin (A), 5 to 80 wt% of the inorganic filler (B), and 5 to 50 wt% of the metal (C) having a low melting point of 300 ° C. or less. This excellent thermoplastic resin composition. The method of claim 1, wherein the thermoplastic resin (A) is polyamide, polyethylene terephthalate, polybutylene terephthalate, polyacetal, polycarbonate, polyimide, polyphenylene oxide, polysulfone, polyphenylene sulfide, polyamide Electromagnetic waves, characterized in that selected from the group consisting of imides, polyethersulfones, liquid crystalline polymers, polyetherketones, polyetherimides, polyolefins, acrylonitrile-butadiene-styrenes, polystyrenes, syndiotactic polystyrenes and mixtures thereof Thermoplastic resin composition excellent in shielding properties. The thermoplastic resin composition according to claim 1, wherein the thermoplastic resin (A) is a crystalline thermoplastic resin. The method of claim 4, wherein the crystalline thermoplastic resin is polyamide, polyethylene terephthalate, polybutylene terephthalate, polyacetal, polyphenylene sulfide, liquid crystal polymer, polyether ketone, polyolefin, syndiotactic polystyrene and mixtures thereof The thermoplastic resin composition excellent in electromagnetic shielding, characterized in that it is selected from the group consisting of. The thermoplastic resin composition according to claim 1, wherein the inorganic filler (B) is a mixture of glass fibers and carbon fibers. The thermoplastic resin composition of claim 6, wherein the inorganic filler (B) is mixed with the glass fiber and the carbon fiber in a weight ratio of 99: 1 to 5:95. The thermoplastic resin composition of claim 6, wherein the glass fiber has a circular, elliptical, square, rectangular, or amorphous shape. The thermoplastic resin composition of claim 8, wherein when the cross section of the glass fiber is square or rectangular, the length of one side is 5 to 50 µm, and the fiber length is 1 to 15 mm. The thermoplastic resin composition of claim 8, wherein the glass fiber has a circular or oval cross section having an average diameter of 5 to 30 µm and a fiber length of 1 to 15 mm. The thermoplastic resin composition having excellent electromagnetic shielding properties according to claim 6, wherein the carbon fiber cross section has an average diameter of 1 to 15 µm and a fiber length of 3 to 12 mm. The metal of claim 1, wherein the metal having a low melting point of 300 ° C. or less is bismuth (Bi), cadmium (Cd), gallium (Ga), indium (In), lead (Pb), tin (Sn), or two or more thereof. It is an alloy comprised, The thermoplastic resin composition excellent in the electromagnetic wave shielding property. The method of claim 12, wherein the (C) is a alloy consisting of an alloy further comprising copper (Cu), aluminum (Al), nickel (Ni), silver (Ag) and two or more in the metal having a low melting point of 300 ℃ or less. A thermoplastic resin composition having excellent electromagnetic shielding properties. The thermoplastic resin of claim 1, wherein the metal having a low melting point of 300 ° C. or less is Sn—Cu, Sn—Ag, Sn—Ag—Cu, Sn—Ag—Cu—Bi alloy. Composition. According to claim 1, At least one additive selected from the group consisting of a heat stabilizer, a release agent, a dispersant, anti-drip stabilizer, weather stabilizer, inorganic filler and inorganic fibers, 0.1 to 10 parts by weight relative to 100 parts by weight of the thermoplastic resin composition. A thermoplastic resin composition having excellent electromagnetic shielding properties. The thermoplastic resin composition as described in any one of Claims 1-15 whose bending modulus is 15-40 GPa, and the electromagnetic wave shielding value is 20-80 dB. A molded article characterized in that the bending modulus produced from the thermoplastic resin composition of claim 16 is 15 to 40 GPa, and the electromagnetic shielding value is 20 to 80 dB.