JPH01247501A - Electrically conductive particles - Google Patents

Abstract

PURPOSE:To improve dispersion stability and electrical conductivity by plating flat fine resin powder having a specified average particle size and specified relations among the major axis size, minor axis size and thickness with a metal. CONSTITUTION:Flat fine resin powder having <=100mum average particle size, 1/1-1/10 ratio of the minor axis size to the major axis size and 1/2-1/50 ratio of the thickness to the major axis size is prepd. and the surface of the resin powder is plated with a metal such as Ag, Cu or Ni to obtain electrically conductive particles. Since the particles have large contact area, improved dispersion stability and electrical conductivity, they are suitable for use in electrically conductive paint.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to conductive particles used in conductive paints for electrical circuits, electromagnetic shielding, and the like.

[Prior art and its problems] Conventionally used conductive particles include various metal powders and conductive carbon, but these conductive particles have a high specific gravity, so they have not been used in conductive paints. However, conductive particles made by plating organic and/or inorganic powder with metals such as silver, copper, and nickel are also known; It is difficult to form a uniform plating layer and it is difficult to obtain high conductivity, and organic powder has a spherical or irregular shape, so when used as a paint, the contact area between particles is small. Therefore, it had the disadvantage of poor conductivity.

The object of the present invention is to provide conductive particles that solve the above problems of dispersion stability and conductivity.

[Means for Solving the Problems] The present invention provides particles having an average particle size of 100 μm or less, and a short axis of 171 to 1/10 of the long axis. This was achieved by discovering that it is possible to provide conductive particles without the above-mentioned drawbacks by plating flat microscopic resin powder with a thickness in the range of 1/2 to 1150 mm of the major axis with metal.

The present invention will be explained in detail below.

In the present invention, the flat microscopic resin powder serving as the core can be obtained by the method described in Japanese Patent Application No. 60-244297, which was previously proposed by the applicant of the present application, or a commercially available powder. In addition, in order to metal plate the flat micro resin powder,
Conventionally known methods can be used, and the metal used is not particularly limited.

Silver, copper, nickel, etc. are preferable in order to obtain high conductivity.

[Function] Since the conductive particles according to the present invention cover the light resin powder with a metal plating layer, the overall specific gravity is reduced, the dispersion stability is improved, and furthermore, the core resin powder is Since the particles are flat, the particles come into contact with each other on the surface, and the contact area is larger than that of conventional point contact made of spheres or irregularly shaped particles, and it is thought that high conductivity can be obtained.

[Example] The present invention will be explained in more detail with reference to Examples below.

In the examples, "1 part" indicates "part by weight."

Spherical nylon (@Higashishi 1, 10 parts, average particle diameter 5 μm), Nylacol NP-10 (Nikko Chemi, 0.1 part, manufactured by Cals Co., Ltd., polyoxyethylene nonylphenyl ether), water
After mixing and stirring 60 parts of the above ingredients, 200 parts of magnetic balls were added.
After mixing for 36 hours, it was filtered and dried to obtain flat micro resin powder with an average major axis of 16 μm, an average minor axis of 13 μm, and an average thickness of 1.6 μm. Next, 12.5 parts of potassium dichromate was heated and dissolved in 100 parts of water, and 50 parts of concentrated sulfuric acid was added with stirring. The above flat resin powder was added to the solution and stirred at 70°C for 15 minutes. After that, the mixture was filtered and washed with water, poured into a 5% aqueous hydrochloric acid solution, stirred for 1 portion, and filtered. Further, this product was added to a mixed solution of 40 parts of Catalyst C (catalytic metal palladium imparting agent, manufactured by Okuno Pharmaceutical Co., Ltd.) and 8140 parts of salt preparation, stirred for 10 minutes, filtered and washed with water, and then sulfuric acid net 29
parts, 25 parts of sodium carbonate, 40 parts of sodium hydroxide,
Add 140 parts of Rossell's salt to 1000 parts of water and add 150 parts of 35% formaldehyde aqueous solution while stirring.
After the reaction was carried out until the color of the liquid almost disappeared, the mixture was filtered, washed with water, and dried to obtain copper-plated flat microscopic nylon.

Daiarashiso main spherical polystyrene (Jumin Chemical Industry 10 parts tmia
, average particle size 15 μm) Near: I-L DLP-10 (Nikko Kei 0.2 parts manufactured by Michals, sodium polyoxyethylene lauryl ether phosphate) Water
After mixing and stirring 40 parts of the above components, the mixture was mixed in an automatic mortar for 5 hours, filtered and dried to obtain flat microscopic resin powder. This item has an average major axis of 24 μm, an average minor axis of 18 μm,
The average thickness was 7 μm. After copper plating was applied to this product in the same manner as in Example 1.

Add 7.5 parts of silver cyanide and 15 parts of sodium cyanide to a solution of 1000 parts of water with stirring, stir for 20 minutes, filter, wash, and dry to obtain silver-plated flat polystyrene. Obtained.

Crushed polyethylene (manufactured by Seitetsu Kagaku @ 10 parts, average particle size 20 μm) 35 parts of benzene The above ingredients were placed in a magnetic pot with a capacity of 300++1 containing 200 g of magnetic balls, mixed for 4 hours, and then filtered. It was dried to obtain flat microscopic resin powder.

This material had an average major axis of 48 μm, an average minor axis of 37 μm, and an average thickness of 24 μm. Next, potassium dichromate 1
2.5 parts were heated and dissolved in 100 parts of water, and 50 parts of concentrated sulfuric acid was added with stirring.The above flat resin powder was added to the solution, stirred at 70°C for 15 minutes, filtered and washed with water, This was poured into a 5% aqueous hydrochloric acid solution, stirred for 1 portion, and filtered.

Further, this product was added to a mixed solution of 40 parts of Catalyst C and 140 parts of concentrated hydrochloric acid, stirred for 10 minutes, and then filtered and washed with water.

Next, 30 parts of nickel sulfate, 30 parts of sodium tartrate,
Add 4 parts of propionic acid to 1000 parts of water and heat to 55°C with stirring, then gradually add 15 parts of sodium hypophosphite, stir for 30 minutes, filter, wash with water, and dry. A flat microscopic polyethylene plated with nickel was obtained.

This was further poured into a solution in which 15 parts of silver nitrate and 150 parts of aqueous ammonia were dissolved in 100 parts of water, and 210 parts of sodium thiosulfate was gradually added without stirring. After stirring for 30 minutes, filtration, washing with water, After drying, silver-plated flat microscopic polyethylene was obtained.

When the surfaces of the conductive particles obtained in Examples 1 to 3 were observed using an electron microscope, it was confirmed that in each case, a metal plating layer covered the flat microscopic resin powder serving as the core.

Application Example 1 60 parts of conductive particles obtained in Example 1 Barracron 8001 (20 parts manufactured by Harima Kasei, adhesive) 20 parts of xylene The above components were mixed and stirred to obtain a conductive paint.

Conductive particles obtained in Example 2 60 parts Barracron 8001 20 parts xylene
20 parts of the above components were mixed and stirred to obtain a conductive paint.

Conductive particles obtained in Example 3 60 parts Barracron 8001 20 parts xylene
20 parts of the above components were mixed and stirred to obtain a conductive paint.

Commercially available silver powder (average particle size 10 μm, 60 parts scaly) Barracron 8001 20 parts xylene 20 parts Mix the above ingredients,
A conductive paint was obtained by stirring.

For comparison, the spherical nylon used in Example 1 was used as it was without being flattened, and after copper plating was applied in the same manner as in Example 1 to obtain conductive particles, conductive paint was prepared in the same manner as in Application Example 3. I got it.

The crushed polyethylene of Skin Comparison Example 3 was used as it is without being flattened, and after silver plating was applied in the same manner as in Example 1 to obtain conductive particles, a conductive paint was applied in the same manner as in Application Example 1. Obtained.

[Effects] Application Examples 1 to 3 and Comparative Examples 1 to 3 were evaluated for dispersion stability and conductivity.

Table: Evaluation results Dispersion stability: The degree of settling of the particles was visually determined after one week at room temperature.

0: No sedimentation X: Completely sedimentation Conductivity: The film was coated and its conductivity was measured.

O: Good Δ: Slightly inferior.

As explained in detail above, the conductive particles of the present invention have good dispersion stability and good current conductivity, so they are suitable for conductive paints.

Claims (1)

[Claims] The average particle diameter is 100 μm or less, and the short axis is 1/1 to 1 of the long axis.
/10, conductive particles characterized by metal plating on flat microscopic resin powder having a thickness in the range of 1/2 to 1/50 of the major axis.