JPH069819A - Resin composition for electromagnetic wave shielding - Google Patents

Abstract

PURPOSE:To obtain a resin composition for shielding electromagnetic wave, having excellent shielding effects on electromagnetic wave and excellent mechani cal characteristics, especially impact strength. CONSTITUTION:100 pts.wt. thermoplastic resin containing electrically conductive fibers is blended with 0.05-30 pts.wt. at least one compound selected from an olefinic wax and an olefinic polymer containing a carboxylic acid anhydride group and/or a carboxyl group to give a resin composition for shielding electromagnetic wave.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a resin composition suitable for electromagnetic wave shielding. More specifically, the present invention relates to a resin composition for electromagnetic wave shielding, which has an excellent electromagnetic wave shielding effect with a small amount of conductive fiber and has excellent mechanical properties, particularly impact resistance.

[0002]

2. Description of the Related Art As a method for making a thermoplastic resin conductive, conductive paint, electromagnetic wave shielding plating, surface treatment such as zinc spraying, metal powder, carbon black, metal flakes, metal coated glass flakes in the thermoplastic resin are used. There is a method of adding and molding a conductive filler such as copper, metal fiber, carbon fiber, and metal-coated carbon fiber.

However, the method of surface treatment with conductive paint, electromagnetic wave shielding plating, zinc spraying, etc., requires a processing step of conducting the conductive treatment on the surface of the molded casing molded article,
Further, it has a defect that the conductive layer is easily peeled off. Also,
The method of molding from a resin composition to which a conductive filler is added is advantageous because it does not require special post-processing and there is no fear of peeling the conductive layer, but there are still various problems. For example, a resin composition to which a particulate conductive filler such as carbon black, metal powder, or metal flakes is added has insufficient conductivity and has a drawback that mechanical properties are significantly deteriorated due to a large amount of addition. is doing. Further, a resin composition containing a fibrous conductive filler such as copper fiber, stainless fiber, carbon fiber or metal-coated carbon fiber has improved mechanical and thermal characteristics, good conductivity, and electromagnetic wave shielding resin composition. It is useful as, but the fibers are easily cut during melt kneading,
It is necessary to increase the addition amount more than necessary amount, and there is a drawback that the specific gravity is increased, the workability is deteriorated, and the cost is increased. Therefore, there is a demand for the appearance of a resin composition for electromagnetic wave shielding which has an excellent electromagnetic wave shielding effect with a small amount of conductive fibers and has good mechanical properties.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electromagnetic wave shielding resin composition having an excellent electromagnetic wave shielding effect and good mechanical properties, especially impact resistance.

As a result of intensive studies to achieve the above object, the present inventor has found that a thermoplastic resin composition containing a conductive fiber has an olefinic wax containing a carboxylic acid anhydride group and / or a carboxyl group. The inventors have found that the addition of a small amount of an olefin-based polymer makes it possible to obtain a resin composition for electromagnetic wave shielding that meets the above-mentioned object, and arrived at the present invention.

[0006]

The present invention comprises an olefin wax and an olefin polymer having a carboxylic acid anhydride group and / or a carboxyl group in 100 parts by weight of a thermoplastic resin composition containing a conductive fiber. The present invention relates to an electromagnetic wave shielding resin composition containing 0.05 to 30 parts by weight of at least one selected compound.

The thermoplastic resin used in the present invention is not basically limited, and a thermoplastic resin used in the case of electronic equipment is preferably used. Examples of the thermoplastic resin include polypropylene resin, styrene resin, modified polyphenylene oxide resin, polyamide resin, polycarbonate resin, polyphenylene sulfide resin, polyester resin and the like. Particularly preferred are, for example, ABS resin, polycarbonate resin, polyethylene terephthalate resin, polybutylene terephthalate resin and mixtures of two or more thereof.

The conductive fiber used in the present invention is not particularly limited, for example, metal fiber such as stainless fiber, aluminum fiber, copper fiber, brass fiber, carbon fiber, metal-coated glass fiber, metal-coated carbon fiber, etc. Is given
Two or more of these may be used in combination. Among them, stainless fiber, copper fiber, and metal-coated carbon fiber are particularly preferable as the conductive resin composition having an excellent electromagnetic wave shielding effect. The metal fiber preferably has a diameter of 6 to 80 μm, more preferably 6 to 60 μm. The diameter of carbon fiber, metal-coated glass fiber, and metal-coated carbon fiber is particularly preferably 6 to 20 μm. Such conductive fibers are preferably surface-treated with a silane coupling agent, a titanate coupling agent, an aluminate coupling agent, or the like. Further, those treated with olefin resin, styrene resin, polyester resin, epoxy resin, urethane resin or the like are preferable, and those treated with epoxy resin or urethane resin are particularly preferable.
If the amount of the conductive fiber added is too small, the conductivity of the electromagnetic wave shielding resin composition will be insufficient, and if it is too large, molding will be difficult. , Usually 0.5 to 30% by volume,
It is preferably 1 to 25% by volume.

The olefin wax or olefin polymer having a carboxylic acid anhydride group and / or a carboxyl group (hereinafter simply referred to as having a carboxyl group) used in the present invention is an olefin wax or an olefin polymer. It is a wax or polymer obtained by acid treatment. Preferred examples of the olefin wax having a carboxyl group include the following formulas.

[0010]

[Chemical 1]

[0011]

[Chemical 2]

[In the formula, n is an integer of 12 to 20. ]
I can give you one. Two or more kinds of olefin waxes and olefin polymers having a carboxyl group may be used in combination, and the addition amount thereof is 0.05 to 30 parts by weight with respect to 100 parts by weight of the resin composition. This addition amount is 0.
If it is less than 05 parts by weight, the electromagnetic wave shielding effect and the impact resistance improving effect are small, and even if it is added in an amount of more than 30 parts by weight, the electromagnetic wave shielding effect and the impact value are not further improved, and conversely the extrudability is lowered. Is not appropriate.

Any method and apparatus can be used for producing the resin composition of the present invention. For example, a method of mixing and pelletizing a mixture of an olefin wax or an olefin polymer having a thermoplastic resin, a conductive fiber and a carboxyl group with a single-screw or twin-screw extruder, a Banbury mixer, a heating roll, injection molding, etc. Or a method of first mixing any two of them and then mixing the remaining one, for example, an electrically conductive fiber and a thermoplastic resin are mixed, and then an olefin wax or an olefin polymer having a carboxyl group. How to mix and use,
Examples include a method of adding conductive fibers to a pellet made of an olefin wax or an olefin polymer having a thermoplastic resin and a carboxyl group, a so-called masterbatch method of adding a master in which conductive fibers are concentrated to a high concentration. .

The resin composition of the present invention contains optional additives such as flame retardants, flame retardant aids, heat stabilizers, antioxidants, light stabilizers, release agents, flow modifiers, colorants and lubricants. A foaming agent or the like may be added in an expression amount as needed. Still other conductive fillers such as carbon black, metal powder,
Metal flakes and the like and reinforcing materials and fillers such as glass fibers, glass flakes, whiskers, aramid fibers, talc, mica, wollastonite, clay, silica, glass powder, calcium carbonate and the like can be used together. Further, other thermoplastic resins, elastic bodies, etc. may be added.

[0015]

EXAMPLES The present invention will be further described with reference to the following examples. The evaluation was performed by the following method. Impact strength: AS
TM D-256 (with Izod notch, thickness 3.2mm)
It was measured by.

Electromagnetic wave shielding effect: side 150 mm, thickness 3 mm
TR-17 made by Advantest Co., Ltd.
A magnetic field wave (frequency 30
0 MHz).

[0017]

Examples 1 to 7 and Comparative Examples 1 to 8 Polycarbonate resins shown in Table 1, conductive fibers and additives were dry blended in the proportions shown in Table 1, and then a uniaxial extruder with a vent having a screw diameter of 30 mm [NAKATANI Machine Manufactured by VSK-30], and melt-kneaded at a cylinder temperature of 300 ° C. to obtain pellets by strand cutting.
After drying at ℃ for 5 hours with a hot air circulation dryer, injection molding machine [Sumitomo Heavy Industries, Ltd .: Nestal SYCAP 480 /
150], the cylinder temperature is 310 ° C., the mold temperature is 10
An impact test piece and an electromagnetic wave shielding test piece were obtained at 0 ° C. The evaluation results are shown in Table 1.

[0018]

Examples 8 and 9 and Comparative Examples 9 and 10 ABS resin or polybutylene terephthalate resin shown in Table 1, conductive fibers and additives were dry-blended at the ratio shown in Table 1, and then extruded at 240 ° C and molded at the molding temperature. A test piece for evaluation was obtained at 240 ° C. The evaluation results are shown in Table 1.

The symbols for resins, conductive fibers and additives in Table 1 are shown below. Further, the parts by weight showing the amount of addition of the additive shows the ratio to the total 100 parts by weight of the resin and the conductive fiber.

PC: Polycarbonate resin [Panlite L-1225 manufactured by Teijin Kasei Co., Ltd.] ABS: ABS resin [Santac UT- manufactured by Mitsui Toatsu Chemicals, Inc.]
61] PBT: polybutylene terephthalate resin [manufactured by Teijin Ltd.
TRB-K] NiCF: Nickel-coated carbon fiber [Besfight MC HTA-C 6-US (I) manufactured by Toho Rayon Co., Ltd., diameter 7.5 μm,
Length 6mm] SUS: Stainless fiber [Naslon SUS manufactured by Nippon Seisen Co., Ltd.]
304, diameter 8 μm, length 6 mm] CF: carbon fiber [Besfight H manufactured by Toho Rayon Co., Ltd.]
TA-C6-U, diameter 7 μm, length 6 mm] A: Olefin wax having a carboxyl group [Mitsubishi Kasei Co., Ltd. Diakarna-30, acid value 75 m]
g KOH / g] B: Olefin wax having carboxyl group [High wax oxidation type 22 manufactured by Mitsui Petrochemical Co., Ltd.]
03 A, acid value 30 mg KOH / g] C: olefin polymer having carboxyl group [Egzero VA-1803 A manufactured by Exxon Chemical Co., maleic anhydride amount 0.65% by weight] D: maleic anhydride [ Wako Pure Chemical Industries, Ltd .; Special grade] E: Olefin wax without carboxyl group [High Wax 200 P from Mitsui Petrochemical Co., Ltd.] F: Olefin polymer without carboxyl group [Mitsui Petrochemical ( Hi-Zex Powder 210 Co., Ltd.
0 JP]

[0021]

[Table 1]

[0022]

The composition of the present invention has an excellent electromagnetic wave shielding effect and excellent mechanical properties, especially impact resistance,
It is suitable for a wide range of industrial fields that require electromagnetic wave shielding, including housings of electronic devices, and the industrial effects produced by it are exceptional.

Claims (1)

[Claims] 1. 100 parts by weight of a thermoplastic resin composition containing a conductive fiber, and at least one compound selected from an olefin wax and an olefin polymer having a carboxylic acid anhydride group and / or a carboxyl group. A resin composition for electromagnetic wave shielding, which comprises 0.05 to 30 parts by weight.