Patent ID: 7786178
Filing Date: 2010-08-31
Classification: B22F,B82Y,H01B,Y10S

Abstract:
1. A process for producing a fine silver particle colloidal dispersion of a water-organic solvent system which comprises: a reaction step of allowing an aqueous silver nitrate solution to react with a mixed solution of an aqueous iron(II) sulfate solution and an aqueous sodium citrate solution to form an agglomerate of fine silver particles; a filtration step of filtering the resultant agglomerate of fine silver particles to obtain a cake of the agglomerate of fine silver particles; a dispersion step of adding pure water to the cake to obtain a first fine silver particle colloidal dispersion of a water system in which dispersion the fine silver particles have been dispersed in the pure water; a concentration and washing step of concentrating and washing the first fine silver particle colloidal dispersion of a water system to obtain a second fine silver particle colloidal dispersion of a water system; and a dilution and viscosity modifying step of adding an organic solvent to the second fine silver particle colloidal dispersion of a water system; wherein after the concentration and washing step, the second fine silver particle colloidal dispersion of a water system, when subjected to ultrafiltration, has an ultrafiltrate that has an electric conductivity of 200 μS/cm or less; in the dilution and viscosity modifying step, said organic solvent comprises dimethyl sulfoxide, and the fine silver particles in said fine silver particle colloidal dispersion of a water-organic solvent system are in a concentration of from 10% by weight to 70% by weight; and said fine silver particle colloidal dispersion of a water-organic solvent system does not contain any polymeric dispersing agent.