Fine Silver Particle Colloidal Dispersion, Coating Liquid for Silver Film Formation, Processes for Producing These, and Silver Film

摘要

A process for producing a fine silver particle colloidal dispersion the fine silver particles of which have a larger average particle diameter than those in the conventional Carey-Lea process and also which has superior dispersion stability. An aqueous silver nitrate solution is allowed to react with a mixed solution of an aqueous iron(II) sulfate solution and an aqueous sodium citrate solution, and the resultant reaction fluid containing an agglomerate of fine silver particles is left at 0 to 100° C. to obtain an agglomerate of fine silver particles having grown into granular particles. Next, this agglomerate of fine silver particles having grown into granular particles is filtered, and, to the resultant cake of the agglomerate of fine silver particles, pure water is added to obtain a fine silver particle colloidal dispersion having an average particle diameter of 20 to 200 nm. This fine silver particle colloidal dispersion is concentrated and washed, further followed by addition of an organic solvent containing dimethyl sulfoxide, to obtain a coating liquid for silver film formation.