JPS6076542A - Electrically conductive resin - Google Patents

Abstract

PURPOSE:A resin, consisting of a resin containing mixed mica powder, coated with Ni with a high dispersibility, and kneaded therein, and having imparted electric conductivity and smooth surface without deteriorating the lightweight property thereof. CONSTITUTION:An electrically conductive resin consisting of a resin containing mica powder, coated with Ni, and kneaded therein. The mica powder coated with Ni has 10-500mu size and 10-50wt% ratio Ni/(Ni+mica). Examples of the resin to be used include polyethylene, phenolic, vinylidene chloride, acrylic, polyester, nylon, polyvinyl chloride, polypropylene, polycarbonate, polystyrene, melamine, urea, silicone resins and fluororesins.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a conductive resin, particularly a conductive resin for electromagnetic shielding. In recent years, electronic circuits have become smaller, more complex, and more precise, and malfunctions and noise have become important problems. Many of the causes of this are electromagnetic waves generated from other parts and circuits, and it has become necessary to shield the intrusion and radiation of these electromagnetic waves, and legal regulations are also being considered. The best way to shield electromagnetic waves is to surround them with conductive materials, and the method of shielding with metal materials has been established since fortune-telling, but recently shielding has been done by imparting conductivity to plastic materials. ing. The following methods are known as methods for making plastic materials conductive.

1. Kneading conductive fillers such as metal powder and carbon black into plastic.

2. Coating the plastic surface with metal (by plating, thermal spraying, etc.).

3. Apply conductive paint to the plastic surface.

-Muiχ×RoI+Dou1-Rejection1t-1hSpec;2diE2-Do1The conductive fillers used so far are as follows:
There are carbon powders, m1lk, AI flakes, Ni powders, Ni-coated carbon TA fibers, Cu or copper fibers, etc., but carbon materials lack conductivity, A1 has no oxidation resistance, and N1-coated carbon fibers. is expensive, and the fillers that are practically used are Ni powder or brass m
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However, the specific gravity of these fillers is 8 or more, and in order to achieve conductivity with an electromagnetic shielding effect when mixed with resin, the conductive filler must be at least 6θ% (by weight), preferably 70%. Therefore, the specific gravity of the resin containing the conductive filler becomes 2 or more, which impairs the lightness of the resin.

In other words, it is desirable that the specific gravity of the conductive filler mixed into the resin is as low as possible.Since conductivity depends on the volume percent of the conductive filler (normally 2o#, around the volume percent is optimal), the specific gravity of the conductive filler is Being small has the advantage that the required amount (weight) of the conductive filler to be included is small.

The non-inventors have taken up mica powder whose surface is coated with Ni as a conductive filler. The advantages of this material are: (1) The specific gravity of mica is approximately 2.8, and the specific gravity of mica coated with Ni is also small; for example, even powder coated with 40% Ni has a specific gravity of approximately 3.9. , the specific gravity is much lower than that of metal powders, so electrical conductivity can be achieved with less weight percent.

2. Mica particles have a flake shape with a diameter of 3 to 2000 μm, and the Ni-coated mica powder also maintains almost this shape, making it easy for the particles to contact each other in the resin, making it conductive at a small weight percent. You can express your sexuality. Furthermore, the mica powder has good dispersibility due to its woody nature, and the N1-coated mica powder also has good dispersibility.

It does not aggregate like metal fibers and easily disperses in resin.

3. Because it is flaky, it is shiny, and when incorporated into resin, the resin surface becomes smooth and has an aesthetic effect.

4. The price of mica is lower than Ni, so Ni-coated mica powder is a cheap conductive filler.

The mica powder used has a particle length of lO~500. It is preferable to use flake-like materials, and the amount of Ni covered is 1 to the weight of mica.
If it is 0 to 50%, the entire surface of mica can be covered, and the electrocardiographic properties will be close to that of Ni alone.

The mica surface can be coated with N1 by electroless plating, or by physical means such as vacuum evaporation or sputtering, but generally electroless plating is used.

Mica has a particle length of 10 to 500 mm. Use the one.

If the mica particle length is smaller than IO, the amount of Ni coating required will increase and the resulting resin will lack aesthetic effect. 500#
The particle size of the mica powder used, which is larger than L and is liable to break during dispersion in the resin, is selected according to the dispersion machine used, the dispersion method, and the properties (including aesthetic properties) of the resulting resin.

In general, mica powder contains fine particles of less than 1 OP, which may cause damage, so it may be desirable to classify and remove them.

In order to mix these Ni-coated mica powders with a resin, both are kneaded using a two-roll machine, an injection molding machine, or the like.

Generally, resins include polyethylene, phenol resin,
Vinylidene chloride, acrylic resin, polyester resin, nylon, polyvinyl chloride, polypropylene, polycarbonate, polystyrene, melamine resin, urea resin, silicone resin, fluororesin, etc., as required.
A silicate or titanate coupling agent, a surfactant, an antioxidant, etc. can be added. It is also possible to add other conductive fillers in combination.

The conductive resin of the present invention can be processed into a sheet and used as an electromagnetic shielding material, and depending on the type of resin, it can also be used as a conductive paint.

The conductive resin of the present invention can also be used as a low temperature heating element.

300 g of flaky mica powder with an average grain size of 40 l was coated with N1t by electroless plating. Electroless plating is 8
According to the Kanigen Ni plating process of Kanigen Co., Ltd., the product was first treated with 1.5 grams of Kanizen Red Schumer's solution as an activation treatment, and then treated with Kanizen Nickel Plating Solution 5R-55 at 60°C for 30 minutes. Ni plated. The amount of plating was 40% by weight based on the weight of the coating powder. The Ni-coated mica powder thus obtained had a specific gravity of 3.6 (measured value) and a specific resistance of 10 −4 Ω·C11, which were almost the same as Ni alone.

This powder was mixed with a predetermined amount of PVC (polyvinyl chloride) resin (Mitsubishi Monsato Kasei C982) and two coals for approximately 130 g.
The mixture was kneaded at ℃ to produce a sheet.

Table 1 shows the conditions and results at that time.

Table 1 1-. 50 100 2 75 100 50 3 100 100 1 4 125 100 0.8 Even if Ni-coated mica powder accounts for 50% by weight, 1
The surface resistance was several ohms 10, and electromagnetic seal 1: characteristics j±sufficient. By the way, the specific gravity of sheet No. 3 is 1.
8, and when the attenuation characteristic was measured for electromagnetic waves of 0.1 to 500 MHz using a spectrum analyzer TR4172 manufactured by Tagada Buken Co., Ltd., it showed 30 to 50 dB, and the shielding effect was sufficient.

Example 2 A flaky mica powder having an average particle size of 100 l was coated with Ni in a manner similar to that described in Example 1.

However, the amount of Ni plating was 25%. The powder thus obtained has a specific gravity of 3.2 and a specific resistance of 10-'Ω・
It was Cm. A sheet was prepared by kneading 40 g of this powder and 60 g of polyethylene using two rolls, and the surface resistance was 1Ω7, and the electromagnetic shielding properties were almost the same as those of the product of Example 1.

Patent applicant Mitsubishi Metals Corporation Agent: Patent Attorney Masahiro Matsui

Claims (1)

[Claims] 1. A conductive resin made of a resin kneaded with Ni-coated mica powder. 2. The conductive resin according to claim 1, wherein the size of the Ni-coated mica powder is 10 to 500 JL, and the Ni/(Ni 10 mica) ratio is 10 to 50% by weight. thing. 3. The conductive resin according to claim 1, wherein the resin is polyethylene, phenol resin, vinylidene chloride, acrylic resin, polyester resin, nylon, polyvinyl chloride, polypropylene, polycarbonate, polystyrene, melamine resin, One selected from the group consisting of urea resin, silicone resin, and fluororesin.