化学还原法制备银粉及其在导电胶中的应用

Preparation of silver powder by chemical reduction method and its application in conductive adhesive

研究化学还原法制备银粉过程中Ag~+浓度、还原液滴加方式、分散体系对银粉形貌的影响机理,获得一款适合用于导电胶制备的银粉。采用硝酸银为银源,分别以明胶、阿拉伯树胶以及聚乙烯吡咯烷酮(简称PVP)和明胶混合体系作为分散剂,研究不同分散体系对银粉形貌及粒径等性能。结果表明银粉粒径随着溶液中Ag~+浓度升高呈现变大趋势;不同分散体系制备的银粉形貌差别较大,而粒径差别不大。以明胶为分散剂制备的银粉为规则的球状,以阿拉伯树胶为分散剂制备的银粉为规则的片簇状,以PVP和明胶混合体系作为分散剂制备的银粉形貌为球状与片状的混合。还原液加入方式对银粉粒径也有较大影响,以一次加入方式制备的银粉粒径分布范围较大。此外,银粉粒径随反应温度升高呈现逐渐变大的趋势。通过对比发现最适合用于导电胶制备的银粉为用以阿拉伯明胶单分散体系制备的球状银粉。化学还原法制备银粉过程中,溶液中Ag^(+)浓度、还原液滴加方式以及分散体系均对银粉形貌和粒径有不同程度的影响,用不同形貌的银粉制备导电胶时的体积电阻率有差别。

The purpose of this study is to prepare silver powder using chemical reduction method,and to investigate the influence mechanism of Ag concentration,reduction liquid droplet addition method,and dispersion system on the morphology of silver powder during the preparation process,in order to obtain a suitable silver powder for the preparation of conductive adhesive.The method used is to prepare silver powder using silver nitrate as the silver source.Gelatin,arabic gum,and a mixture of polyvinyl pyrrolidone(PVP)and gelatin are used as dispersants to study the effects of different dispersion systems on the morphology and particle size of silver powder.The results showed that the particle size of silver powder showed an increasing trend with the increase of Ag*concentration in the solution;The morphology of silver powder prepared by different dispersion systems varies greatly,while the particle size difference is not significant.The silver powder prepared by one-time addition has a larger particle size distribution range.The silver powder prepared with gelatin as the dispersant is in a regular spherical shape,while the silver powder prepared with arabic gum as the dispersant is in a regular cluster shape.The silver powder prepared with a mixed system of PVP and gelatin as the dispersant has a mixture of spherical and sheet-like morphology.In addition,the particle size of silver powder shows a gradually increasing trend with the increase of reaction temperature.The most suitable silver powder for the preparation of conductive adhesive is spherical silver powder prepared using Arabic gelatin monodisperse system.The conclusion drawn is that the concentration of Ag^(+) in the solution,the method of adding reducing solution droplets,and the dispersion system all have varying degrees of influence on the morphology and particle size of silver powder during the preparation of silver powder by chemical reduction method.The volume resistivity of conductive adhesive prepared with different morphologies of silver powder varies.