Preparation of Nano-silver Dispersion Liquid for Water-based Conductive Ink

Nano-silver dispersion liquid for water-based conductive ink was prepared by chemical reduction method in aqueous solutions,using NaH2PO2·H2O as deoxidizer,PVP(polyvinylpyrrolidone) as polymeric protective agent,and sodium hexametaphosphate as dispersing agent.Dosage of deoxidizer,protective agent and dispersing agent as well as influence of temperature on particle size and shape of nano-silver were studied through L9(33) orthogonal test.The optimal conditions to prepare the nanosized silver dispersion liquid was as follow: under the conditions of AgNO3 concentration was 1.0 mol/L,n(NaH2PO2·H2O)/n(AgNO3) was 2.5∶1,n(PVP)/n(AgNO3) was 1.5∶1,n(sodium hexametaphosphate)/n(AgNO3) was 0.007∶1,the temperature was 40 ℃.The nano-silver dispersion liquid with its size distribution between 15 nm and 60 nm was obtained through SEM and Malvern Laser particle size analyzer after standing 30 days,which overcomes the problem of easy flocculation in water-based conductive ink.