Silver micropowder, silver ink, silver coating, and methods for production of these materials

摘要

Provided is a silver micropowder coated with a protective material and capable of more drastically reducing the sintering temperature than before. The silver micropowder comprises silver particles processed to adsorb hexylamine (C6H13—NH2) on the surfaces thereof and having a mean particle diameter DTEM of from 3 to 20 nm or an X-ray crystal particle diameter DX of from 1 to 20 nm. The silver micropowder has the property of forming a conductive film having a specific resistivity of not more than 25 μΩ·cm when it is mixed with an organic medium to prepare a silver coating material and when a coating film formed of it is fired in air at 120° C. Even when fired at 100° C., it may form a conductive film having a specific resistivity of not more than 25 μΩ·cm. The silver micropowder can be produced by mixing a silver particle dispersion, as monodispersed in an organic medium, of silver particles coated with a primary amine A having an unsaturated bond and having a molecular weight of from 200 to 400, and hexylamine, and then keeping the mixture at 5 to 80° C. with stirring to thereby form precipitated particles.

主权项

1. A method for producing a silver micropowder comprising
a step of reducing a silver compound with a reducing agent of an alcohol or polyol under presence of an amine A having an unsaturated bond and having a molecular weight of from 200 to 400 to obtain coated silver particles with the primary amine A having a mean particle diameter DTEM of from 3 to 20 nm or an X-ray crystal particle diameter DX of from 1 to 20 nm, a step of mixing the silver particles coated with the primary amine A with a liquid organic medium to be silver particles monodispersed in the liquid organic medium, a step of mixing the silver particle dispersion and hexylamine, a step of keeping the mixture liquid at 5 to 80° C. with stirring to thereby form precipitated particles, and a step of collecting the precipitated particles as a solid fraction through solid-liquid separation.