Лако-красочные материалы — производство

Bismuth oxychloride is produced by the hydrolysis of very acidic (pH < 1.0) bis­muth solutions in the presence of chloride. The crystal quality can be varied by

careful adjustment of bismuth concentration, temperature, pH, pressure, reactor geometry, and addition of surfactants. The usually tetragonal bipyramidal struc­ture can be flattened to platelets with a high aspect ratio. Products with an aspect ratio of 10-15 show low luster and a very good skin feel and are used as fillers in cosmetics. Crystals with higher aspect ratios show an exceptional luster and are mainly used for nail polish [4, 6-8].

The low light stability, the fast settling caused by the high density of 7.73 g/cm3, and the lack of mechanical stability limit the use of BiOCl in technical applica­tions. Therefore, it is mainly used in cosmetics, but also in buttons and jewelry.

The light stability can be improved to some extent by cerium doping and UV absorbers.