Hectorite Clay - a unique, multi-purpose rheological additive Part 1 - Chemistry and Properties

摘要

SOME of the earliest applications that utilize "clay" date back to antiquity. Clay tokens were used for record keeping purposes, bricks were made from clay mud and clay pottery had a practical use as well as a decorative purpose . Other typical uses of clay minerals in ancient time were in applications such as bleaching, laundry, cosmetics, medicine, porcelain etc. Some of these uses are still relevant today. Although old, the sophisticated nature of these clay applications should not be underestimated. The ancient Maya blue pigment is perhaps a good example of early nanotechnology where clay is used to stabilize an indigo dye . An organic - inorganic surface complex is formed when indigo dye binds to the clay surface during pigment preparation. Unlike the dye alone, this combined clay-dye complex is remarkably stable and does not fade when exposed to harsh weathering conditions. Furthermore, the clay-indigo color is resistant to acids, bases, chemical solvents and does not biodegrade. Other pigment systems can be formulated for use in coatings based on such dye-clay complexes and as such might offer an environmentally friendly alternative next to pigments currently used in the coatings industry.