Лако-красочные материалы — производство

The first commercially successful synthetic pearlescent pigments were hexagonal lead salt crystals, especially basic lead carbonate Pb(OH)2 x 2 PbCO3. Basic lead carbonate is precipitated from aqueous lead acetate with carbon dioxide under carefully controlled reaction conditions. The resulting platelets are less than 0.05 pm thick and show hexagonal dimensions of about 20 pm, yielding an aspect ratio of > 200. Because of their high refractive index of 2.0 and their even surface, they exhibit a very strong luster. If the thickness of the platelets is increased by slightly modified reaction conditions, interference colors can be obtained [4, 6-8].

The crystals are very fragile and are handled only in dispersions. They settle very fast because of their density of 6.14 g/cm3. The use of basic lead carbonate is also limited by its low chemical stability, the toxicity of its by-products, and toxico­logical concerns in its application areas.