Лако-красочные материалы — производство

Special effect pigments with neutral body color, high luster, and improved spark­ling properties can be achieved from borosilicate flake substrates (glass flakes) [45, 46]. These pigments consist mostly of calcium-aluminium borosilicate plate­lets coated with metal-oxide layers such as SiO2, TiO2 or Fe2O3. The synthetically manufactured flakes can be absolutely planar and show a smooth surface. They have a relatively uniform thickness of each single particle and therefore, in most cases, a homogeneous color of each platelets. The substrate particles, as a whole, show a thickness deviation from platelet to platelet caused by the production pro­cess. The manufacture of glass flakes that show a thickness in the range from sev­eral hundred nanometers to more than 10 pm is carried out starting from molten glass of the desired composition. The flakes are formed from the melt, for exam­ple, by cooling a free-falling curtain of the molten glass that is uniform in thick­ness and temperature [47]. Borosilicate flakes can also be formed from molten material by feeding the stream in a downward direction into a rotating cup [48].

7.3