Patent ID: 7053126

Claim:
A process for producing a noble-metal type fine-particle dispersion which contains a solvent and noble-metal type fine particles having an average particle diameter of from 1 nm to 100 nm and dispersed in the solvent, said noble-metal type fine particles being any of fine particles of a noble metal selected from gold, silver, platinum, palladium, rhodium and ruthenium; blended fine particles made up of a blend of two or more kinds of fine noble-metal particles; fine alloy particles containing two or more kinds of noble metals; and noble-metal-coated fine silver particles, surface-coated with any of the noble metals except silver, in which a plurality of primary particles of the noble-metal type fine particles stand agglomerated in the form of chains to make up chainlike agglomerates, wherein; the process comprising the steps of: an agglomeration step of adding a hydrazine solution to a dispersion in which primary particles of noble-metal type fine particles have been made to stand monodisperse in the solvent, to destabilize the dispersibility of the noble-metal type fine particles in the dispersion by the action of the hydrazine and cause the plurality of primary particles in the noble-metal type fine particles to agglomerate in the form of chains to obtain a dispersion of chainlike agglomerates; and a stabilization step of adding a hydrogen peroxide solution to the dispersion of the chainlike agglomerates obtained, to decompose and remove the hydrazine to stabilize the dispersibility of the chainlike agglomerates in the dispersion.