Hydrated Zinc Borates and Their Industrial Use

Abstract

Zinc borates are important chemical products having industrial applications as functional additives in polymers, bio-composites, paints and ceramics. Of the thirteen well documented hydrated binary zinc borates, Zn[B3O4(OH)3] (2ZnO∙3B2O3∙3H2O) is manufactured in the largest quantity and is known as an article of commerce as 2ZnO∙3B2O3∙3.5H2O. Other hydrated zinc borates in commercial use include 4ZnO∙B2O3∙H2O, 3ZnO∙3B2O3∙5H2O and 2ZnO∙3B2O3∙7H2O. The history, chemistry, and applications of these and other hydrated zinc borate phases are briefly reviewed, and outstanding problems in the field are highlighted.