JP2000129148A - Resin composition for shielding electromagnetic wave - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resin composition for shielding an electromagnetic wave excellent in mechanical characteristics, molding property, appearance of a molded product and coloring property. SOLUTION: This resin composition for shielding an electromagnetic wave comprises (A) 100 pts.wt. thermoplastic resin (a rubber-reinforced styrenic resin or a mixture of the rubber-reinforced styrenic resin and other thermoplastic resin), (B) 5-30 pts.wt. fiber covered with a metal, (C) 3-20 pts.wt. zinc oxide whisker and (D) 0.5-10 pts.wt. titanium oxide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a resin composition for shielding electromagnetic waves. More specifically, the present invention relates to a resin composition for electromagnetic wave shielding excellent in mechanical properties, moldability, molded article appearance, and colorability, which is obtained by blending metal-coated fibers, zinc oxide whiskers, and titanium oxide.

[0002]

2. Description of the Related Art In general, a method for making a thermoplastic resin conductive is a method of subjecting a molded resin article to a surface treatment such as conductive paint, electromagnetic wave shielding plating, zinc spraying, or the like. And a method in which a conductive filler such as metal powder, carbon black, metal flake, metal fiber, carbon fiber, etc. is blended and molded. However, since the surface treatment method requires a processing step of conducting a conductive treatment on the surface of the molded resin molded product, the conductive treatment is particularly complicated for a resin molded product having a complicated shape, and the conductive layer is easily peeled off. And the like. In addition, a method of molding from a resin composition containing a conductive filler does not require special post-processing, and is advantageous because the conductive layer does not have to be peeled off. However, for example, a resin composition containing a particulate conductive filler such as carbon black, metal powder, or metal flake has insufficient conductivity, and the mechanical properties are significantly reduced due to the large amount of the resin composition. have. In addition, the resin composition containing a fibrous conductive filler such as metal fiber and carbon fiber has improved mechanical and thermal properties, and has better conductivity than the case where a particulate conductive filler is blended. It is useful as a resin composition for shielding electromagnetic waves, but has the drawback that fibers are easily cut during melt-kneading, the blending amount must be increased more than necessary, and moldability and appearance of a molded product are deteriorated.

[0003] Further, in applications requiring these electromagnetic wave shielding properties, for example, in game machines and the like whose demand has been increasing in recent years, the design is also required, and therefore, a resin composition having particularly excellent coloring properties is desired. I have. However, at present, a resin composition for shielding electromagnetic waves having excellent coloring properties has not been obtained. Therefore, there is a demand for an electromagnetic wave shielding resin composition having an excellent electromagnetic wave shielding effect and having excellent mechanical properties, molding fluidity, surface appearance, and coloring properties.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electromagnetic wave shielding resin composition having an excellent electromagnetic wave shielding effect and having excellent mechanical properties, molding fluidity, surface appearance and coloring. And

[0005]

Means for Solving the Problems The inventors of the present invention have made intensive studies to achieve the above object, and as a result, by blending metal-coated fibers, zinc oxide whiskers and titanium oxide with a thermoplastic resin, a mechanical The present inventors have found that an electromagnetic wave shielding resin composition having excellent mechanical properties, moldability, molded article appearance and coloring properties can be obtained, and have reached the present invention. That is, according to the present invention, the metal-coated fiber (B) is 5 to 30 parts by weight, and the zinc oxide whisker (C) is 100 parts by weight of the thermoplastic resin (A).
The present invention relates to a resin composition for shielding electromagnetic waves, comprising 3 to 20 parts by weight and 0.5 to 10 parts by weight of titanium oxide (D).

As the thermoplastic resin used in the present invention, HIPS resin, ABS resin, AES resin,
Examples include rubber-reinforced styrene resins such as AAS resins and MBS resins, polycarbonate resins, polybutylene terephthalate resins, polyethylene terephthalate resins, polyamide resins, polypropylene resins, polyphenylene oxide resins, and polyphenylene sulfide resins.
Among these, it is particularly preferable to use a rubber-reinforced styrene-based resin or a mixture of a rubber-reinforced styrene-based resin and another thermoplastic resin. The mixing ratio when mixing the rubber-reinforced styrene resin with another thermoplastic resin is not particularly limited. However, the mixing ratio is 5 to 100% by weight of the rubber-reinforced styrene resin and 0 to 95% by weight of the other thermoplastic resin. Preferably, the content is 10 to 100% by weight of a rubber-reinforced styrene resin and 0 to 90% by weight of another thermoplastic resin.

The metal-coated fiber (B) used in the present invention includes nickel-coated carbon fiber, nickel-coated glass fiber and the like, and nickel-coated carbon fiber is particularly preferable. In the present invention, ordinary carbon fibers, glass fibers and the like may be blended together with the metal-coated fibers as long as the effect is not impaired.

The zinc oxide whiskers (C) used in the present invention preferably have a tetrapot-type crystal structure. The zinc oxide whiskers may be surface-treated with a coupling agent such as a silane coupling agent, a titanate coupling agent, or an aluminum coupling agent, if necessary.

As the titanium oxide (D) used in the present invention, there are a rutile type and an anatase type, and both can be used, but those having a rutile type crystal structure are particularly preferable. These titanium oxides are usually surface-treated with aluminum, silica, a silane coupling agent, a titanate coupling agent, silicon oil, or the like.

The resin composition of the present invention comprises metal-coated fibers (B) 5 to 3 with respect to 100 parts by weight of the thermoplastic resin (A).
0 parts by weight, 3 to 20 parts by weight of zinc oxide whiskers (C) and 0.5 to 10 parts by weight of titanium oxide (D). When the amount of the metal-coated fiber (B) is less than 5 parts by weight, the electromagnetic wave shielding effect is inferior, and when it exceeds 30 parts by weight, the mechanical strength and the moldability are inferior. When the zinc oxide whisker (C) is less than 3 parts by weight, the electromagnetic wave shielding effect is poor, and
When the amount is more than the weight part, the mechanical strength and the moldability are inferior and are not preferable. If the content of titanium oxide (D) is less than 0.5 part by weight, the coloring property is poor, and if it exceeds 10 parts by weight, the mechanical strength and the moldability are poor, and the electromagnetic wave shielding effect is unfavorably impaired.

The resin composition of the present invention comprises the above (A)
The components (B), (C) and (D) can be obtained at once, or by a method in which any two or three components are previously mixed and then the remaining components are mixed. In addition, at the time of mixing, mixing can be performed using a known mixer, for example, a single-screw or twin-screw extruder, a Banbury mixer, a kneader, a roll, or the like.

The resin composition of the present invention contains optional additives such as a heat stabilizer, an antioxidant, a light stabilizer, a flame retardant, a flame retardant auxiliary, an anti-drip agent, a release agent, a plasticizer, and a colorant. , Lubricant,
A foaming agent or the like may be blended as necessary.

[Examples] The present invention will be further described below with reference to examples, but the present invention is not limited thereto. In addition, each evaluation in this invention was performed by the following method.

[0014]Impact resistance: According to ASTM D-256
Izod impact strength without notch on 1/8 inch specimen
Was measured.Formability (Minimum filling pressure): SAV-1 manufactured by Yamashiro Seiki Seisakusho
00 Using an injection molding machine,
The filling pressure was determined. The minimum filling pressure is
Injection pressure (molding machine gauge pressure)
Show. Molding temperature: 230 ° C Mold temperature: 50 ° C Injection speed: 50%Colorability : 100 parts of the following dyes are added to the thermoplastic resin (A)
0.05 parts by weight per part by weight
Fiber, zinc oxide whisker, titanium oxide
50 × 7 obtained by molding the obtained resin composition under the above molding conditions.
A 5 × 3 (mm) flat plate was visually judged. Used here
The dye was red, Sumiplast Red H, manufactured by Sumika Color Co., Ltd.
FG Blue: Sumiplast Blue O manufactured by Sumika Color Co., Ltd.
R Yellow: Sumiplast Yellow manufactured by Sumika Color Co., Ltd.
HLR. : All three colors can be visually differentiated and clear
is there. ×: One or more of the three colors are unclear and difficult to classify.
It is.appearance : Molded according to the molding conditions shown in the above moldability evaluation method
Using a flat plate of 50 × 75 × 3 (mm)
And visually evaluated. : The gloss of the mirror surface of the molded product is 70% or less
Above, and a local pool of fibers was seen in the visual judgment.
Not possible ×: The gloss of the mirror surface of the molded article is 70% or less, or visually
In some cases, a local pool of fibers is seenElectromagnetic shielding  Electromagnetic wave shielding effect Molded according to the molding conditions shown in the moldability evaluation method above.
Using a 150 × 150 × 2 (mm) flat plate,
The center of a flat plate in an electric field at 500 MHz by the strike method
Was measured for its electromagnetic wave shielding effect. The numerical value in the table is sun of n = 5.
The average value of the pull. In the same way as the stability method, the electromagnetic wave shielding effect at both ends of the flat plate
(Average value of n = 5), and the measured value at the center of
When the difference is within ± 20%, it is marked as “○”, while the difference is within ± 20%.
Those that are 20% or more are marked with x.

-Thermoplastic resin (A)-A-1: ABS resin (Clarastic GA-704 manufactured by Sumika ABS Latex Co., Ltd.) A-2: Above ABS resin and polycarbonate resin (Sumitomo Dow Co., Ltd.) Caliber 200-20) and 50/50
Were mixed at the ratio of A-3: The above ABS resin and polyamide resin (Nylon 6 A-1030BRL manufactured by Unitika Ltd.) were mixed with 50 /
They were mixed at a ratio of 50. A-4: The above ABS resin and polybutylene terephthalate resin (Duranex 4 manufactured by Polyplastics Co., Ltd.)
00FP) in a ratio of 50/50.

-Metal coated fiber (B)-B-1: Nickel coated carbon fiber (Toho Rayon Co., Ltd.)
Manufactured by Vesfight MCHTA-C6-US) Bi: carbon fiber (Vesfight HTA-C6-SR manufactured by Toho Rayon Co., Ltd.)-zinc oxide whisker (C)-C-1: Panatetra manufactured by Matsushita Amtech Co., Ltd. -Titanium oxide (D)-D-1: RTC-30 manufactured by Great Lakes Chemical Corporation

[0017]

Examples 1 to 5 and Comparative Examples 1 to 6 (A) to (D)
The components were mixed at the ratios shown in Table 1 and melt-kneaded using a twin-screw extruder to obtain pellets. Various test pieces were prepared from the obtained pellets using an injection molding machine, and each evaluation was performed. In addition, about the test piece for colorability evaluation, the pellet obtained by mix | blending 0.05 part each of three types of dyes at the time of said melt-kneading was used. Table 1 shows the results.

[0018]

[Table 1]

[0019]

The composition of the present invention has excellent coloring properties and electromagnetic wave shielding effects, and is excellent in moldability, surface appearance and mechanical strength, and is effective in shielding electromagnetic waves including electronic equipment housings. It can be suitably used in a wide range of required industrial fields, and is industrially useful.

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Claims (3)

[Claims] 1. A metal-coated fiber (B) of 5 to 30 parts by weight, a zinc oxide whisker (C) of 3 to 20 parts by weight and a titanium oxide (D) based on 100 parts by weight of the thermoplastic resin (A).
An electromagnetic wave shielding resin composition comprising 0.5 to 10 parts by weight. 2. The resin composition for shielding electromagnetic waves according to claim 1, wherein the thermoplastic resin (A) is a rubber-reinforced styrene-based resin or a mixture of a rubber-reinforced styrene-based resin and another thermoplastic resin. 3. The electromagnetic wave shielding resin composition according to claim 1, wherein the metal-coated fibers are nickel-coated carbon fibers.