JPS60147480A - Conductive coating composition - Google Patents

Abstract

PURPOSE:To obtain the titled composition both low in the specific gravity and electrical resistance, of small settlement, which high shielding effect, by incorporating Ni-plated mica powder instead of Ni powder in thermoplastic and/or thermosetting resin. CONSTITUTION:The objective composition can be obtained by incorporating (A) 100pts.wt. of thermoplastic resin (e.g. acrylic resin) and/or thermosetting resin (e.g. epoxy resin) with (B) pref. 20-500pts.wt. of nickel-plated mica powder (pref. with a size <=80 mesh) and, if necessary, (C) filler pigment such as silicon oxide. In the incorporation of the component (B) in the component (B), it is recommended to use a diluent solvent such as methyl isobutyl ketone.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a conductive coating composition that exhibits little sedimentation, low specific gravity, and low resistance.

In recent years, as the density and performance of ICs and LSIs have increased, a large number of ICs and LSIs have come to be used in electronic devices.

However, since high-frequency pulses are generated from these ICs and LSIs, surrounding televisions, radios, and peripheral devices are affected by these pulses, causing image distortion, noise, malfunction, etc., and this has become a problem.

Furthermore, televisions, radios, and the like are similarly affected not only by high-frequency pulses from ICs and LSIs, but also by electromagnetic waves generated from automobiles, high-voltage lines, and the like.

As the electromagnetic environment worsens year by year, the need to shield electromagnetic waves is increasing.

There are two methods for shielding electromagnetic waves: one is to apply conductive paint to the housing of an electronic device to protect it from electromagnetic waves entering from the outside, and the other is to suppress electromagnetic waves generated from the device itself.

Nickel and carbon are used as conductive paints.

It is known that conductive powders such as silver and copper are dispersed in resin. Among these, carbon is cheap but has poor conductivity, and silver powder has excellent conductivity but is very expensive. Copper powder has a good balance between price and conductivity, but paints using copper powder have the disadvantage that the copper powder oxidizes during storage or application, resulting in a decrease in resistance. .

On the other hand, it has a relatively good balance between conductivity and price.

Nickel powder has excellent stability, and is currently widely used as the main conductive paint for electronic device housings.

However, with conductive paints that use nickel powder, the specific gravity of the nickel powder is high, so the nickel powder settles during paint storage and painting operations, making workability difficult and making it easy for the painted surface to become uneven. There were many shortcomings.

As a result of various studies, the present inventors found that if nickel-plated mica powder was used instead of nickel powder, sedimentation of the paint could be prevented.

That is, the present invention relates to a conductive coating composition containing (A) a thermofusible resin and/or a thermosetting resin and (B) nickel-plated mica powder.

Examples of the thermofusible resin used in the present invention include thermofusible acrylic resins, vinyl resins, urethane resins, polyester resins, hydrocarbon resins, fluoroelastomers, cellulose resins, and the like. Examples of thermosetting resins include thermosetting acrylic resins, unsaturated polyester resins, epoxy resins, urethanes, resins, and alkyd resins. Two or more of these resins may be used together,
A thermoplastic resin and a thermosetting resin may also be used together.

The nickel-plated mica powder of component (B) has a particle size of 30 mesh or less, preferably 80 mesh or less. Nickel-plated mica powder with a particle size of more than 30 mesh has a poor appearance after painting. For example, nickel-plated mica powder is produced by forming a nickel film on mica powder by electroless plating.

Mitsubishi Kin JlK-Shado's 'l'H-300. There is nickel-plated mica powder made by Noguco ■.

The blending ratio of the pseudo) component and the (B) component of the present invention is (A) component 1
The amount of component B) is preferably in the range of 20 to 500 parts by weight per 00 parts by weight. If component (B) exceeds 500 parts by weight, it tends to be difficult to form a base, and if it is less than 20 parts by weight, the conductivity tends to decrease.

In addition to components (A) and (B) of the present invention, diluent solvents include toluene, xylene, acetone, methyl ethyl ketone, methyl imbutyl ketone, methyl alcohol, ethyl alcohol, and ethyl cellosol.

Commonly used solvents such as butyl cellosolve and aliphatic solvents can be used. Silicon oxide, if necessary
Filler pigments such as titanium oxide, calcium carbonate, and magnesium carbonate are also used.

In addition to the nickel-plated mica powder of component (8), copper powder, silver powder, copper-zinc alloy powder, etc. may be used in combination as necessary.

Next, the present invention will be explained by examples. Example.

Comparative Example Middle indicates parts by weight.

1. Synthesis of thermofusible acrylic resin A 250 parts of methyl methacrylate and 150 parts of toluene were mixed with lI
! Prepare the four roses in a paraple flask.

The temperature was raised to 90° C. and kept at that temperature while passing nitrogen gas. Polymerization was carried out while a solution containing 200 parts of methyl methacrylate and 3 parts of azobisisobutyronitrile was added dropwise to the mixture over a period of 2 hours. After that, the temperature was raised to 110℃, kept for 2 hours to complete polymerization, cooled, and when the temperature reached 50℃, 90% of toluene was added.
0 part was added and stirred for 10 minutes to obtain a solution of thermoplastic acrylic resin A.

Comparative Example 1 100 parts of the solution of thermofusible acrylic resin A obtained in 1.
60 parts of nickel powder (manufactured by Fukuda Metal Foil & Powder Industry ■, carbonyl Ni 287, average particle size 51 chrome).

Composition A was obtained by mixing and stirring 36 parts of methyl isobutyl ketone.
And so.

Example 1 100 parts of the solution of acrylic resin A obtained in 1., 60 parts of nickel-plated mica powder (manufactured by Nopco, average particle size 0.2, nickel content 50 qb, specific gravity 4.1), 36 parts of methyl isobutyl ketone. were mixed and stirred to obtain 1 Composition B.

Example 2 Composition C was prepared by mixing and stirring 100 parts of the solution of thermofusible acrylic resin A obtained in 1, 100 parts of the nickel-plated mica powder used in Example 1, and 50 parts of methyl isobutyl ketone.

Coating composition A prepared in the above comparative examples and examples.

B and C were placed in an 18 mmφ glass test tube to a height of 10 ann and left at 25°C. The height of the supernatant colorless transparent resin liquid layer was measured at predetermined intervals.

In addition, 9 compositions A, B, and C were coated on a Noryl substrate at 25°C.
Dry for 24 hours at 10mm x 100mm x 0.
I IIIm coating and 150 Peng X 150 Peng X O,1
A coating film of - was formed.

The volume resistivity of the former coating film was measured, and the shielding effect of the latter coating was measured using a spectrum analyzer manufactured by Takeda Riken Kogyo ■.

The results are shown in Table 1.

Table 1 From the above results, it is shown that the conductive paint composition of the present invention has less sedimentation and has conductivity and shielding effect equivalent to that of conventional nickel-based paints.

Claims (1)

[Claims] 1. A conductive coating composition comprising (Al) a thermofusible resin and/or a thermosetting resin and (B) nickel-plated mica powder.