JPS58221206A - Manufacture of electrically conductive powder for electrically conductive paint - Google Patents

Abstract

PURPOSE:To obtain inexpensive electrically conductive powder for electrically conductive paint with superior electric conductivity and corrosion resistance by dispersing a composition contg. coarse alloy powder and fatty acid in an org. solvent and wet grinding the composition. CONSTITUTION:Coarse alloy powder contg. Zn, Sn, Al, Be, Si or In, Ag, and Cu is manufactured by spraying molten metal or by other method. A composition contg. the powder and 0.05-30wt% fatty acid such as stearic acid or palmitic acid basing on the amount of the powder is prepared. The composition is dispersed in an org. solvent such as acetone or cyclohexanol and wet ground with a rotary ball mill or the like. The ground material is subjected to centrifugal separation, and the resulting solid phase is air-dried to obtain alloy powder for electrically conductive paint. Electrically conductive paint contg. the alloy powder as electrically conductive powder shows high electric conductivity and superior migration resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing conductive powder used in a conductive paint made of conductive powder 1 and a synthetic resin and a solvent, and an object of the present invention is to provide a conductive paint that is inexpensive and has excellent conductivity and corrosion resistance. It is something.

Conventionally, this type of conductive paint contains A as a conductive powder.
Noble metal powders such as U, Mug, and Pd have been used. Generally, Ag is used as a conductive powder and mixed with a thermosetting resin such as phenol resin, epoxy resin, or xylene resin, and a solvent such as ethyl calpitol, and then the paint is screen printed onto a phenolic resin substrate. After applying the coating using methods such as methods, it is heated and cured to form electrodes for variable resistors, etc.
It has also been used as a printed wiring conductor for electronic circuits.

However, in recent years, as electronic devices have become smaller and thinner, there has been a trend toward smaller electronic components. The interaction between atmospheric moisture and the DC electric field causes a phenomenon in which Ag moves between mug paint electrodes, so-called migration, which causes short circuits and is often a major cause of trouble. .

In order to compensate for these drawbacks of Ag paint, Ag-P
(Although conductive paint using i-powder is commercially available,
It's still not perfect. Furthermore, conductive paint using Ag-P (1 powder) is not economically viable due to the fact that the price of Pd is extremely high compared to the price of Ag, and in recent years the price of precious metals, especially Ag, has skyrocketed. This is extremely disadvantageous.

For the reasons mentioned above, it is hoped that an inexpensive conductive paint with good migration resistance will emerge.3 Under these circumstances, the inventors first developed an alloy powder mainly composed of base metals. As a result of investigation, Ag-Zn-
Cu alloy powder + Ag 5n-Cu alloy powder, Ag-AP
-Cu alloy powder, Ag-Be-Cu alloy powder, Ag-3i
It was discovered that a conductive paint using -Cu alloy powder and Ag-In-1n alloy powder as conductive powder has excellent migration resistance and satisfies conductivity at a considerable level. However, depending on the manufacturing conditions of the metal alloy powder described above, there were cases where the conductivity was poor.

The present invention has been made in view of the above points, and the inventors have developed a method for mixing metal alloy coarse powder and this metal alloy powder with a ratio of 17% and 0.
．． It has been discovered that a conductive paint using a metal alloy powder as a conductive powder obtained by dispersing a composition containing 05 to 30% by weight of fatty acids in an organic solvent and then wet-pulverizing the composition exhibits good conductivity. .

Conventionally, it has been known that conductive powder used in this type of conductive paint preferably has a scaly or flattened shape. As a method for obtaining metal powder in such a shape, a method of pulverizing it using a machine such as a rotary mill or a vibrating mill has been known for a long time. However, in the grinding of the metal alloy coarse powder mainly composed of base metals according to the present invention, when dry grinding is performed, metal alloy powder whose surface is excessively oxidized is obtained, and when used as a conductive paint. Good conductivity may not be obtained, or when dry grinding is performed with the addition of grinding aids such as fatty acids, the coarse metal alloy powders may aggregate with each other, resulting in insufficient grinding. Even when wet pulverization is performed in an organic solvent, there are still problems such as obtaining metal alloy powder whose surface is excessively oxidized.

The present invention solves the above-mentioned problems in the method for producing conductive powder by combining a coarse metal alloy powder and a composition containing 0.06 to 30% by weight of fatty acids with respect to the coarse metal alloy powder. By dispersing it in a solvent and then mechanically pulverizing it, a metal alloy powder with a low degree of surface oxidation can be obtained, which is suitable as a conductive powder for conductive paint. The fatty acids are stearic acid, palmitic acid, myristic acid, lauric acid, oleic acid, erucic acid, linoleic acid, and Riff 6 Pesolenic acid, and the organic solvent is acetone.

Cyclohexanol, methanol, ethanol.

Good results are obtained with propatool, butanol and toluene. It is unclear why good results can be obtained by mechanically grinding a mixed solution of fatty acids and an organic solvent as a dispersion medium, but a thin layer of fatty acids is formed on the surface of the alloy metal, which prevents excessive oxidation. It is thought that the dispersibility of the metal alloy powder is improved by the organic solvent. The lower limit of the amount of fatty acid added is the minimum amount that can exhibit its effect; if the amount added exceeds the upper limit, the pulverized product after pulverization becomes viscous, resulting in poor workability.

The pulverized product obtained by the above method is centrifuged to separate the same phase and liquid phase, and the solid phase is air-dried to obtain a metal alloy powder for conductive paint. Fatty acids are attached to the surface of the metal alloy powder obtained in this way, and if the amount of fatty acids attached becomes large, it tends to have a negative effect on the conductivity of the cured paint film when used as a conductive paint. , 7 Z-- After the above-mentioned natural drying, further drying under reduced pressure, etc.
It is desirable to remove fatty acids adhering to the surface of metal alloy powder. In particular, when the amount of fatty acid added exceeds 3% by weight based on the metal alloy coarse powder, the effect of vacuum drying is recognized.

Next, the present invention will be described in detail according to Examples.

Ag-Zn-Sn alloy, Ag-3n-A/alloy, Ag-
Al-Cu alloy, Ag-Be-Cu alloy, Ag-8i
Metal alloy coarse powder such as -Cu alloy and Ag-In-Cu alloy was produced as follows. Depending on the predetermined alloy composition, hg, Zn, Sn, Al, Be,
Si, In, and Cu materials were weighed and all floors were designated as IMy (Ap, Be.

Sl is...? 1zoit Cu-Az Shun Alloy, Cu-
Be alloy.

(Added by Cu-Si master alloy). This was dissolved in nitrogen gas and then pulverized by a molten metal spraying method. Nitrogen gas was used as a spray medium, and the mixture was cooled in water. The obtained powder was dried to obtain coarse metal alloy powder.

The particle size of the metal alloy coarse powder is about 5 to 10,011.

Coarse metal alloy powder obtained by the above-mentioned method contains stearic acid, palmitic acid, myristic acid, lauric acid, oleic acid, erucic acid, and linoleic acid.

and a predetermined amount of fatty acid lylunic acid, and about 8001 agate stones with a diameter of 2 to 3 CTL were transferred to an alumina pot with an internal volume of 21 L7.
To this, organic solvents such as acetone, cycloexanol, methanol, ethanol, propatool, butanol, and toluethane were added to the extent that the agate was immersed (approximately 300 cc), and the rotation time was 160 hours using a rotary ball mill method. was crushed. After pulverization, the contents of the pot were taken out, the agate was removed, the contents were separated into a solid phase and a liquid phase using a centrifuge, and the same phase was air-dried.

The metal alloy powder thus obtained has an average particle size of 1 to 3
μ, the shape was oblate. If necessary, the obtained metal alloy powder was dried under reduced pressure at 250° C. for 1 hour under reduced pressure of about 1 mmHg.

The metal alloy powder 2y- obtained by the method described below is
Xylene resin 1! ? , Ethylcalpitol 0.2! ? At the same time, the mixture was kneaded using a Huba-Mala. Kneading with a Hubermala was carried out by repeating 40 revolutions four times under a load of 100 pounds.

The conductive paint prepared above was printed in a predetermined shape on a phenolic resin substrate-1 using a 200 mesh screen, and then cured by heating at 190° C. for 10 minutes in the air.

The results of measuring the resistance values between both ends of the above printed pattern are shown in the following table. The following table also shows the results when the metal alloy powder was made into a paint using the metal alloy powder obtained by crushing the metal alloy coarse powder in the same manner using only an organic solvent as a dispersion medium without adding fatty acids. .

(hereinafter referred to as gold and white) 10:-11': As is clear from the above explanation and table, the conductive paint using the metal alloy powder as conductive powder produced by the method of the present invention has good conductivity. It is of great value in providing an economically inexpensive conductive paint with excellent rigid migration properties.

Claims (5)

[Claims] (1) Metal alloy coarse powder and this metal alloy coarse powder: 1-0.
A method for producing conductive powder for conductive paint, which comprises dispersing a composition containing 6 to 30% by weight of fatty acids in an organic solvent and then wet-pulverizing the composition. (2) Claim (1), wherein the fatty acid is any one of stearic acid, valmitic acid, myristic acid, lauric acid, oleic acid, erucic acid, linoleic acid, and linolic acid. Method for producing conductive powder for conductive paint. (3) The organic solvent is acetone or cyclohexanol. methanol, ethanol, propatool, butanol,
The method for producing conductive powder for conductive paint according to claim (1), characterized in that the powder is toluene. (4) Claim No. 1, characterized in that the conductive powder is a metal 2-peno alloy powder produced by molten metal spraying.
A method for producing conductive powder for conductive paint as described in Section 1. (5) The metal alloy is Zn, Sn, Muz, Be, S
The method for producing a conductive powder for conductive paint according to claim (1), wherein the conductive powder is a metal alloy containing any one of i and In, Ag and Cu.