JPH0573783B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a resin composition having excellent electrical properties, moldability, and heat resistance for use in housings and electrical/electronic parts constituting electrical/electronic equipment. In recent years, electrical and electronic devices have become smaller, lighter, and thinner, and with this, various properties such as electromagnetic shielding, electrical insulation, magnetic permeability, heat resistance, and moldability have improved. There is a need for materials that satisfy both of these requirements. Generally, conductive fillers are added to resins to give them electromagnetic shielding properties, but if the amount added is small, the electromagnetic shielding effect is small;
If the amount added is large, the electromagnetic wave shielding effect will be large, but there will be problems such as conductivity resulting in lower electrical insulation and poor moldability. Therefore, it has been difficult to simultaneously satisfy electromagnetic wave shielding properties, electrical insulation properties, and moldability. Furthermore, it is generally known that the heat resistance and molding processability of a resin are contradictory, and that when the heat resistance of the resulting resin composition is improved, the molding processability is reduced. For this reason, the present inventors have conducted various studies on resin compositions that simultaneously satisfy the above-mentioned properties, and have found a magnetic material with a specific mixing ratio of aromatic polysulfone resin, hard ferrite, magnetic metal such as iron powder, and soft ferrite. The present inventors have discovered that by adding a specific amount of a powder mixture, a resin composition can be obtained that has electromagnetic wave shielding properties over a wide frequency range and has good electrical insulation, magnetic permeability, and moldability, and has completed the present invention. . That is, the present invention uses aromatic polysulfone resin 100
Weight part and mixture of three types of magnetic powders: hard ferrite, magnetic metal powder, and soft ferrite 30~
300 parts by weight, and the mixing ratio of the above three magnetic materials is 40 to 60 parts by weight of hard ferrite, 15 to 35 parts by weight of magnetic metal, and 15 parts by weight of soft ferrite.
Heat resistance, electromagnetic shielding property, which is the ratio of ~35 parts by weight
This is a heat-resistant resin composition for electrical and electronic devices with excellent electrical insulation and moldability. The aromatic polysulfone resin used in the present invention is a type obtained by, for example, a condensation reaction between an alkali phenolate group and an aromatic halogen group activated with an electron-withdrawing sulfone group in an aprotic polar solvent. It is a linear polymer with three essential bonding units: arylene bonds (aromatic bonds), ether bonds, and sulfone bonds. For example, a very typical example has the following structure.

[Table] These polyallylsulfone resins can be easily produced by the methods described in, for example, Japanese Patent Publications No. 40-10067, Japanese Patent Publication No. 42-7799, and Japanese Patent Publication No. 47-617. In the present invention, it is particularly preferable to use polyether sulfone represented by the above formula (1) from the viewpoint of heat resistance and moldability. The hard ferrite used in the present invention is
A rare earth-based magnetic material such as Ba-based, Sr-based, or Sm-Co-based magnetic material is used. As the magnetic metal powder, Ni permalloy, Mo permalloy, and iron, which have high magnetic permeability, are particularly preferred. Also, as a soft ferrite
Mn-Zn system, Mg-Zn system, Ni-Zn system, etc. can be used. In particular, it is preferable to use Sr type hard ferrite and Mn-Zn type as soft ferrite. The mixing ratio of these three types of magnetic powder used in the present invention is determined by considering the electromagnetic shielding frequency range, electrical insulation properties, and moldability required for the final product: 40 to 60 parts by weight of hard ferrite, 40 to 60 parts by weight of hard ferrite, The ratio is selected within the range of 15 to 35 parts by weight of metal and 15 to 35 parts by weight of soft ferrite. If the proportion of hard ferrite is less than this mixing ratio, the electromagnetic wave shielding property will not be sufficient, and if it is too large, the volume resistivity will become too large and the electromagnetic wave shielding property will vary from product to product, which is not preferable. The amount of these magnetic powder mixtures added in the present invention is based on 100 parts by weight of aromatic polysulfone resin.
The amount is 30 to 300 parts by weight, preferably 50 to 250 parts by weight.
If the amount is less than this, the electromagnetic wave shielding properties will be poor,
If more than 300 parts by weight is added, problems such as a decrease in electrical insulation properties of the resulting resin composition and deterioration of molding properties are undesirable. In order to add the specified magnetic powder to the aromatic polysulfone resin of the present invention, the aromatic polysulfone resin and the magnetic powder are generally mixed using a general mixer such as a Henschel mixer, and then pelletized using a general extruder. This is done by making In addition, stabilizers, ultraviolet absorbers, lubricants, and colorants may be mixed into the heat-resistant resin composition of the present invention as long as they do not impair the quality of the resin composition. The heat-resistant resin composition of the present invention is molded by a known molding method such as an injection molding method, an extrusion molding method, a compression molding method, or a rotational molding method, and is put into practical use. Molded products obtained by melt-molding the heat-resistant resin composition of the present invention have excellent electromagnetic shielding properties and electrical insulation properties, and can be widely used in the fields of electrical and electronic equipment. The present invention will be specifically explained below using Examples. Examples 1 to 3 and Comparative Examples 1 to 3 Polyether sulfone resin (abbreviated as PES) as aromatic polysulfone resin [VICTREX PES
200P (trademark)], Sr-based ferrite as a hard ferrite, iron powder as a magnetic metal, and Mn-Zn-based as a soft ferrite in the amounts shown in Table 1 were added and mixed in a Henschel miscer. Thereafter, the mixture was extruded into strands using a single-screw extruder to form pellets. This pellet was used to mold a 50 mm square box and lid using an injection molding machine. A magnetic field generating coil was installed inside the box, and a catch coil was installed outside. Electromagnetic wave shielding performance was measured by passing a 10 ⁵ Hz current through the magnetic field generating coil and detecting the current generated in the catch coil. The volume resistivity of this lid was also measured. The results are shown in Table-1.

[Table] Comparative Examples 4-5 Polyethersulfone resin (abbreviated as PES) as aromatic polysulfone resin [VICTREX PES]
200P (trademark)], Sr-based ferrite as hard ferrite, iron powder as magnetic metal, and Mn-Zn-based as soft ferrite in the amounts shown in Table 2, and mixed with a Henschel mixer. The mixture was extruded into strands using a single-screw extruder and pelletized. Using this pellet, a 50 mm square box and lid were molded using an injection molding machine, and the electromagnetic wave shielding properties of the box and the volume resistivity of the lid were measured in the same manner as in the examples. The results are shown in Table-2. As shown in Table 2, in the case of Comparative Example 4, the electromagnetic wave shielding property was poor, and in the case of Comparative Example 5, the volume resistivity was too large, and the variation in electromagnetic wave shielding property from product to product was large.

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Claims (1)

[Claims] 1 For 100 parts by weight of aromatic polysulfone resin,
It consists of 30 to 300 parts by weight of a mixture of three types of magnetic powders: hard ferrite, magnetic metal, and soft ferrite, and the mixing ratio of the three types of magnetic substances is 40 to 60 parts by weight of hard ferrite, magnetic metal.
A resin composition for electrical/electronic equipment having a ratio of 15 to 35 parts by weight of soft ferrite and 15 to 35 parts by weight of soft ferrite.