Dispersion of metal nanoparticles, method for producing the same, and method for synthesizing metal nanoparticles

Patent metadata

Field	Value
Publication number	US-9580811-B2
Application number	US-201514725828-A
Country	US
Kind code	B2
Filing date	May 29, 2015
Priority date	Feb 27, 2007
Publication date	Feb 28, 2017
Grant date	Feb 28, 2017

Abstract

The present invention aims to provide a method for producing a dispersion of metal nanoparticles which enables to control the shape and the particle diameter over a wide range, a dispersion of metal nanoparticles having superior dispersion stability, and a method for producing the same. In addition, the present invention further aims to provide a dispersion of metal nanoparticles which has a volume resistivity of 2×10 −6 to 6×10 −6 Ω·cm and is suitable for use as an electrically conductive material, and a method for producing the same. Moreover, the present invention further aims to provide a method for synthesizing metal nanoparticles which can produce metal nanoparticles suitable for use as electrically conductive materials by synthesizing the metal nanoparticles from a insoluble metal salt which is free of corrosive materials.

First claim

The invention claimed is:

1. A method for synthesizing metal nanoparticles, comprising the steps of:
preparing an aqueous metal salt solution (A) by dissolving a metal salt, said aqueous metal salt solution (A) consisting essentially of the metal salt and a solvent;
preparing an aqueous carboxylic acid solution (B) by dissolving one type or two or more types of compounds selected from the group consisting of, citric acid, maleic acid, and salts thereof;
preparing an aqueous reducing agent solution (C) by dissolving one type or two or more types of compounds selected from the group consisting of formic acid and salts thereof;
mixing the aqueous carboxylic acid solution (B) with the aqueous metal salt solution (A) so as to obtain a suspension of a carboxylic acid salt in which poorly-soluble carboxylic acid salt precipitates; and
forming metal nanoparticles by adding and mixing the aqueous reducing agent solution (C) with the suspension of the carboxylic acid salt,
wherein the aqueous solutions (A), (B), and (C) are separately prepared,
metal elements contained in the metal salt comprise 75% by mass or more of silver, and
the mixing with the aqueous reducing agent solution is carried out by stirring at a temperature of 25 to 95° C.

2. The method for synthesizing metal nanoparticles according to claim 1 , wherein one type or two or more types of metals selected from the group consisting of gold, platinum, palladium, and ruthenium are included as the remainder of the metal elements contained in the metal salt of the aqueous metal salt solution (A) other than silver.

3. The method for synthesizing metal nanoparticles according to claim 1 ,
wherein an amount of carboxylic acid, an amount of carboxylic acid salt, or a total amount of carboxylic acid and carboxylic acid salt contained in the aqueous carboxylic acid solution (B) is within a range from 0.3 to 3.0 mol relative to 1 mol of the metal element contained in the aqueous metal salt solution (A), and
an amount of reducing agent contained in the aqueous reducing agent solution (C) is within a range from 0.1 to 3.0 mol relative to 1 mol of the metal element.

4. A method for producing a metal film, comprising the steps of:
obtaining a dispersion of metal nanoparticles by dispersing the metal nanoparticles which are obtained by the synthesis method according to claim 1 in a dispersion medium; and
forming a metal film by coating the dispersion of metal nanoparticles as a composition for producing a metal film on a base material by a wet coating process.

Assignees

• Mitsubishi Materials Corp

Inventors

• Yamasaki Kazuhiko
• Katagiri Airi
• Arai Masahide
• Takata Yoshiaki
• Hayashi Toshiharu

Classifications

• B22F1/0545

  Dispersions or suspensions of nanosized particles · CPC title

• B22F1/0022

  Operations & Transport · mapped topic

• H01L31/022425

  Electricity · mapped topic

• H01L31/022408

  Electricity · mapped topic

• C23C18/54 Primary

  Contact plating, i.e. electroless electrochemical plating · CPC title