JPS6055037A - Electroconductive molding material - Google Patents

Abstract

PURPOSE:To improve weather resistance, reliability, etc., by adding a powder of a metal which is above the metal of a filler in the series of ionization tendency to an electromagnetic wave-shielding electroconductive molding material based on a thermoplastic synthetic resin and an electroconductive filler. CONSTITUTION:The purpose electroconductive molding material is prepared by mixing a thermoplastic synthetic resin such as polystyrene or polypropylene with electroconductive filler (e.g., long fiber of a metal such as copper or iron) and 0.1-10wt% antioxidant comprising a powder of a metal (e.g., tin or zinc) which is above the metal of the electroconductive filler in the series of ionization tendency. This electroconductive molding material is excellent in an electromagnetic wave-shielding effect and can be suitably used as a housing of an electric device, office machine, telephone or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION [1] Technical Field of the Invention The present invention relates to a conductive molding material that has excellent weather resistance and high reliability.

[Technical difficulties of the invention and its problems] Shielding electromagnetic waves generated from electronic devices [1] Injection molding of housings for electronic devices, etc. using metal filler in thermoplastic synthetic resin However, when metal fillers are added to thermoplastic synthetic resins,
Furthermore, because of injection molding, the metal filler is exposed to high temperatures of 200° C. or more twice, which has the disadvantage that the surface of the metal filler is oxidized and its electrical conductivity decreases to 1 [1]. In addition, during practical use after injection molding, the surface oxidation of the metal filler progresses due to the external environment, particularly heat generated by internal electronic circuits, moisture absorption by the resin, etc., and the electromagnetic shielding effect deteriorates over time. Furthermore, surface oxidation can be prevented by surface treatment of metal fillers, and by adding rust preventives to resins, it is possible to form complexes on metal surfaces and prevent oxidation. However, these methods do not satisfy the conductivity t' that is most required for molding materials for electromagnetic shielding.
There was a drawback that l was difficult to 4rf.

"Eleventh object of the invention" The object of the present invention was made in view of the above-mentioned drawbacks, and
The present invention aims to provide a conductive molding material for electromagnetic shielding that has excellent weather resistance and high reliability.

[Summary of the Invention] As a result of extensive research in order to achieve the above-mentioned object, the present invention achieves the above-mentioned object by using a metal powder that has a greater ionization tendency than the metal of the conductive filler used. This is what I discovered.

That is, in the present invention, in a conductive molding material containing a thermoplastic synthetic resin and a conductive filler as main components, a metal powder having a larger ionization tendency than the metal of the conductive +41 filler is added as an antioxidant by 0.1%. It is a conductive molding material characterized by containing ~10% of polymers.

Examples of the thermoplastic synthetic resin used in the present invention include HeB
Examples include S resin, polystyrene resin, polypropylene resin, polyphenylene oxide resin, modified polyphenylene oxide resin, and the like, but are not particularly limited.

The conductive filler used in the present invention is preferably a metal in the form of a long fiber string. Coating metals such as silver, copper, iron, lead, nickel, etc. on the surface of long lengths of metals such as copper, iron, nickel, and aluminum, or glass cords, carbon fibers, and boron binding cords. It also includes those who did. The diameter of the fiber is not particularly limited, but the thinner the fiber, the more effective it is.

Further, the oxidation-preventing metal powder used in the present invention includes all metals that can be used by the general public as long as they have a higher b ionization tendency than the metal of the conductive filler. It is also important to select a metal that is stable even when added to the thermoplastic resin. As these metal powders, for example, silver, copper, iron, lead, tin, nickel, zinc, etc. are used. Using each of the above ingredients, Lianden↑
Method for manufacturing one molded monthly yield (Well, it can be easily manufactured by mixing each component and using the same method as ordinary molding materials.The molding material of the present invention can be used for housings of electronic equipment, office equipment, telephones, etc. Can be used for

[Embodiment 1 of the invention Hereinafter, the present invention will be specifically explained with reference to Examples.

Example 1 A conductive molding material was prepared by mixing 70% polyester non-resin, 1liH28fIi fi% copper as a conductive filler, and 2% by weight lead powder as an antioxidant metal powder.

A molded article was formed using the obtained molding material, and the volume resistivity of the molded article after being heated at 70° C. and heated at 40° C. and 5% RH for a certain period of time was measured to evaluate weather resistance.
The results are shown in Table 1.

Example 2 Polystyrene resin 68@hanging%, nickel plated glass@
@28% by weight and 4% by weight of zinc powder as antioxidant metal powder were sufficiently mixed to obtain a conductive molding material. Molded articles were molded using this molding material, and the volume resistivity of each was measured in the same manner as in Example 1.

The results are shown in Table 1.

Comparative Examples 1 to 3 According to the composition shown in Table 1, one containing no antioxidant metal powder and an organic antioxidant benzotriazole were added to form a complex on the surface of the conductive filler, and Example 1
In the same manner as above, the volume resistivity of the molding material and molded product was measured using a helmet. The results are shown in Table 1.

5- [Effects of the Invention] As can be seen from the above explanation and Table 1, the conductive i11 molding material of the present invention has excellent weather resistance, high reliability, and excellent electromagnetic shielding effect. I understand that there is something.

The molded phase separation of the present invention is suitable for housings of electronic devices and the like.

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Claims (1)

[Claims] 1 Thermoplastic (1) In a conductive molding material containing a synthetic resin and a conductive filler, a metal powder having a larger ionization tendency than the metal of the conductive bamboo filler is added as an antioxidant by 0.1 to 10%. It is characterized by containing 1-1% conductive material.
(1 molded monthly interest rate.