JPH0743965B2 - Conductive resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a conductive resin composition.

[Conventional technology]

2. Description of the Related Art In recent years, with the miniaturization and refinement of electronic parts, various kinds of conductive functional parts such as conductive adhesives, conductive paints and conductive films have been actively developed. To impart conductivity to these raw materials, gold, silver, copper,
Various methods have been tried in which powdered or fibrous good conductors made of metal or alloy such as nickel and aluminum, or metal-coated mica powder, carbon powder, glass powder and the like are mixed as a filler. However, among these fillers, the carbon material lacks conductivity, and the conductivity of the metal-coated mica powder, carbon powder, glass powder, etc. is greatly influenced by the particle size and shape of the powder, and the shape is adjusted. It is necessary to prepare a homogeneous fine powder, but it is very difficult to satisfy it at present. Therefore, in reality, metal fibers and nickel powder are used, but they all have a large specific gravity, and it is usually necessary to add about 20% by volume in order to achieve the expected conductivity when mixed with fat. As a result, the weight of the molded product becomes very large, which leads to an unfavorable result from the point of reducing the weight of the molded product by the resin.

Further, as a relatively lightweight conductive resin composition having excellent mechanical and thermal characteristics, a mixture of nickel-plated wollastonite in a synthetic resin is known (Japanese Patent Laid-Open No. 59-168044). ).

However, a mixture of nickel-plated wollastonite in a synthetic resin as described above tends to have a large friction coefficient, and sufficiently satisfies the sliding characteristics required as a material for a conductive paint or a conductive film. It wasn't.

[Problems to be solved by the invention]

Thus, in the conventional conductive resin composition, the specific gravity of the filler is large and the weight cannot be reduced by using the resin, and the sliding property is inferior, and the required mechanical strength, conductivity, and There is a problem that none of them satisfy all the friction and wear characteristics.

[Means for solving problems]

In order to solve the above problems, in the present invention,
In a conductive resin composition obtained by mixing nickel-coated wollastonite in a synthetic resin, the nickel-coated wollastonite is fibrous with an average fiber length of 10 to 100 μm and an aspect ratio of 10 or more, and is coated. The amount of nickel is 10 to 70 of the total weight of wollastonite and nickel coating.
This is a method in which the weight percent is adopted. The details will be described below.

First, the wollastonite of the present invention is a natural product or artificial product of a chain silicate also called wollastonite, which is a substance represented by CaSiO ₃ and has an average fiber length of 10 to 100 μm and an aspect ratio of 10 or more. Is preferred. In order to coat the surface of such fibrous wollastonite with nickel, electroless (chemical) plating, or a physical method such as vacuum deposition or spattering may be used. Many have been implemented. The amount of nickel coated is 10 with respect to the total amount of wollastonite and nickel coating.
It is desirable to be 70% by weight. This is because when the nickel coating amount is less than 10% by weight, sufficient conductivity cannot be obtained, and when the nickel coating amount is more than 70% by weight, no improvement in conductivity due to the increase is observed and the weight increases, which is not preferable. This is because, if it is in the range of 10 to 70% by weight, the entire surface of wollastonite can be covered temporarily, and the conductivity close to that of nickel itself can be exhibited. If the fiber length of wollastonite is shorter than 10 μm, the required amount of nickel to coat will be large, and the aesthetics of the composition formed will be impaired. Conversely, if it is longer than 100 μm, it will be kneaded into the resin. It is easily cut when dispersed, and has a large friction coefficient in terms of sliding characteristics, and cannot be used as a sliding material. And if the aspect ratio is less than 10, the conductivity is not satisfied.

Next, the synthetic resin in the present invention is not particularly limited as long as it has been used as a sliding material in each direction as a resin having a relatively small coefficient of friction, and examples thereof include polyethylene and polypropylene. Starting with general-purpose polyolefin, phenol resin,
Polyester, Epoxy resin, Polyamide (Nylon), Polycarbonate, Polyoxymethylene, Silicone resin, Polyimide, Polyamideimid, Polyetherimide, Polyether sulfone, Polyether ether ketone, Polyphenylene sulfide, Polyarylate, Fluorine resin Examples of such thermosetting or high temperature thermoplastic resins may be mentioned, and one or more of these may be selected and used.

To mix nickel-coated wollastonite with such a synthetic resin, use a commonly used device such as a twin-screw melt extruder or an injection molding machine, and add the nickel-coated wollastonite to the prepreg or molten resin. It suffices to mix them, and at this time, if necessary, additives such as a coupling agent, a surfactant, an antioxidant, or other conductive fillers may be appropriately used in combination without any problem.

〔Example〕

The raw materials used in Examples and Comparative Examples are as follows. That is, polyphenylene sulphate (PPS) [US Phillips Petroleum, Inc .: Ryton P4] Polyoxymethylene (POM) [Polyplastics: Zyukon M90-71] Polybutylene terephthalate (PBT) [Mitsubishi Kasei: Novator 5010] Polyamide (nylon 12) [Daicel Chemical Co., Ltd .: Daiamide L1640] phenol resin [Sumitomo Bakelite Co., Ltd .: Sumicon]
PM-8200J] Nickel-coated wollastonite [Maruwa Biochemical Co., Ltd .: Chemolite, average fiber length 25 μm, average fiber diameter 3
μm, nickel coating amount by electroless plating method 40% by weight] Brass fiber [Aisin Precision Co., Ltd .: Aisin Metal Fiber, average fiber length 3 mm, average fiber diameter 60 μm] Nickel coated mica [Lepco: S325, electroless nickel 40 % By weight].

Mixing ratio (volume ratio) of these raw materials as shown in the table
The mixture was mixed in, fed to a twin-screw melt extruder, melt-mixed, and then pelletized using a granulator. The pellets are applied to an injection molding machine to produce test pieces specified in the following test methods, and the volume specific resistance value (Ω · cm), wear coefficient (× 10 ⁻¹⁰ cm ³ / kg · m), The friction coefficient and bending strength (kg / cm ² ) were measured, and the results are also shown in the table.

The test method is as follows.

Volume resistivity: JIS-K6911 Friction coefficient: Suzuki abrasion tester, speed 32m / min, PV value 100kg / cm ² m / min, atmosphere dry, mating material SUJ-2 Friction coefficient: Suzuki friction tester, speed 10 m / min, PV value 100 kg / cm ² · m / min, atmosphere dry, mating material SUJ-2 Bending strength: ASTM-D790 From the above results, Examples 1 to 5 are compared with Comparative Examples 1 to 3 above. It is clear that the four types of physical property values do not show any extreme variations, have appropriate mechanical strength, and are extremely excellent in terms of both conductivity and sliding characteristics.

〔effect〕

As described above, since the conductive resin composition of the present invention has a predetermined amount of fibrous nickel-coated wollastonite with a predetermined physical property, it is required as a material such as a conductive paint or a conductive film. It is a composition that satisfies the sliding characteristics of the low friction coefficient, that is, has all the excellent mechanical strength, friction and wear characteristics, and electrical conductivity, and that the weight reduction from the specific gravity of wollastonite (about 2.8) is achieved. Since it does not significantly impede, the significance of the present invention can be said to be extremely great.

Claims (1)

[Claims] 1. A conductive resin composition comprising a synthetic resin mixed with nickel-coated wollastonite, wherein the nickel-coated wollastonite has an average fiber length of 10 to 10
A conductive resin composition, which is in the form of fibers having an aspect ratio of 10 or more at 0 μm, and the amount of nickel coated is 10 to 70% by weight of the total weight of wollastonite and nickel coating.