JPS61141762A - Electrically conductive molding material - Google Patents

Abstract

PURPOSE:To provide an electrically conductive molding material which has excellent long-term stable electrical conductivity and is suitable for use as a material for shielding undesired electromagnetic waves, by providing a metallic layer other than Al on the surface of an Al fiber to form an electrically conductive filler and uniformly dispersing the filler in a thermoplastic resin. CONSTITUTION:An aluminum fiber prepd. by drawing or melt spinning is degreased and pickled to roughen the surface of the fiber. A metallic layer (e.g. nickel or chromium layer) other than aluminum is formed on the surface of the aluminum by electroless plating, wet plating or vacuum metallizing to prepare an electrically conductive filler. 5-100pts.wt. said filler is uniformly dispersed in 100pts.wt. thermoplastic resin to obtain the desired electrically conductive molding material. The molding material can be widely used in the fields of articles requiring electrical conductivity or electromagnetic wave shielding properties, such as a planar heating element and a cabinet for electronic equipment.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a conductive molding material suitable as a material for shielding unnecessary electromagnetic waves emitted from electronic equipment.

(Prior Art) It has been widely practiced in the past to mix conductive fillers having various shapes into thermoplastic resins to impart conductivity.

For example, JP-A-57-36154 describes that impact resistance can be improved by blending aluminum flakes with a polyamide resin and further blending an ethylene copolymer.

Further, Japanese Patent Application Laid-Open No. 68-78499 discloses a resin material for electromagnetic shielding which is formed by uniformly blending metal fibers with resin self-destruction ζ.

Typical metal fiber materials include copper, brass, iron, aluminum, etc., but aluminum is superior in that it does not impair lightweight, which is one of the advantages of molding resin materials.

In addition, in terms of shape, fibrous fillers have the advantage that superior conductivity can be obtained with a relatively small amount of addition, and there is less deterioration in physical properties than fillers in the form of flakes or powders.

From these points, aluminum fibers are one of the most promising conductive fillers to be mixed into resins.

(Problem to be solved by the invention) However, when aluminum fiber is used as a conductive filler, the long-term stability of conductivity is lower than that of iron fiber or brass fiber, and It has the disadvantage that in order to obtain conductivity, it is necessary to add a large amount.

Particularly in terms of long-term stability, the conductivity decreases significantly when the environmental temperature conditions are varied, which is one of the major problems.

In contrast, attempts have been made to treat the surface of metal fibers using silane-based or titanate-based coupling agents, but satisfactory results have not yet been obtained.

(Means for Solving the Problems) The present inventors have achieved the present invention as a result of intensive research to improve the drawbacks of the prior art.

That is, the present invention is a conductive molding material made by uniformly dispersing a conductive filler formed by forming a metal layer other than aluminum on the surface of aluminum fibers in a thermoplastic resin.

The present invention will be explained in detail below.

Examples of the thermoplastic resin used in the present invention include IJ such as polyester, polyamide, polycarbonate, polyolefin, polyphenylene oxide, polyphenylene sulfide, acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer, etc.
I or two or more types can be mentioned.

The aluminum fiber used in the present invention is not particularly limited as long as it has aluminum as its main component;
Use one containing the above.

Examples of methods for producing aluminum fibers include a drawing method, a melt spinning method, and a cutting method.

The shape of the aluminum fibers may be any shape as long as it can be mixed into resin and molded, especially injection molded.
Use fibers with a diameter of 100μ or less and a fiber length of 5w or less.

The metal layer formed on the surface of the aluminum fiber is not particularly limited as long as it is other than aluminum, and may include gold, silver, copper,
Examples include chromium and nickel.

Among these metals, nickel is particularly preferred.

Methods for forming a metal layer on the aluminum metal surface include wet blating, which is typified by electroless plating called chemical plating and electrolytic plating, vacuum evaporation,
Examples include dry brating methods such as ion blating and sputtering, but electroless plating is usually used.

When forming the metal layer, it is preferable to roughen the surface of the aluminum fibers by degreasing and pickling in order to enhance the anchoring effect and increase adhesion.

Usually, the degreasing treatment is carried out in a triclene steam bath, and the pickling is carried out using a mixed aqueous solution of nitric acid and hydrofluoric acid and an aqueous nitric acid solution.

In addition, for aluminum fibers with a metal layer formed, 15
It is preferable to perform heat treatment at 0° C. for about 1 hour in terms of improving adhesion and corrosion resistance.

The amount of aluminum added to the thermoplastic resin is usually 5 to 10 parts by weight of aluminum fiber per 100 parts by weight of the thermoplastic resin.
0 parts by weight, preferably 10 to 80 parts by weight.

In addition, the method for uniformly dispersing the raincoat is not particularly limited, but may be melt-kneaded using a single-screw or multi-screw extruder, for example.
Alternatively, it may be directly kneaded during molding.

(Effects of the Invention) The four-electroconductive molding material of the present invention can be used in applications that require conductivity and electromagnetic shielding properties, for example, as a surface heating element, or in electronic applications such as communication devices, measuring instruments, and computers. It can be widely used for equipment cabinets, etc.

(Example) Hereinafter, the present invention will be described in more detail using Examples. 40 parts by weight of aluminum fibers with a fiber length of 30 μm and a fiber length of 2 mm were blended and melt-kneaded using a full-flight semi-screw extruder at a cylinder temperature of 220° C. to obtain pellets. Next, using the obtained pellet, acrylonitrile-butadiene-
Injection molding was performed under the conditions of styrene copolymer resin.

Physical properties of the obtained molded product and 1 hour at 85°C.

Volume comparison example 1 when heat cycle treatment of 28°C x 1 hour, -30°C x 1 hour, and 28°C x 1 hour was repeated 1 Fiber diameter 80 μm based on 100 parts by weight of acrylonitrile-butadiene-styrene copolymer resin .

After blending 40 parts by weight of aluminum fibers with a fiber length of 2 m and pelletizing them in the same manner as described in Example I to obtain a molded product, the physical properties and volume when heat cycle treatment is repeated are determined. Changes in resistivity were measured.

Table-2 Kanebo Gosen Co., Ltd.

Claims (2)

[Claims] (1) A conductive molding material made by uniformly dispersing a conductive filler made by forming a metal layer other than aluminum on the surface of aluminum fibers in a thermoplastic resin. (2) The material according to claim 1, wherein the metal layer other than aluminum is a nickel layer.