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) [5.153, 5.154]. These pigments consist mostly of calcium-aluminum borosilicate platelets coated with metal oxide layers such as SiO2, ТЮ2 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 platelet. The substrate particles as a whole show a thickness deviation from platelet to platelet caused by the production process. The manufacture ofglass 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 [5.155]. Borosilicate flakes can also be formed from molten material by feeding the stream in a downward direction into a rotating cup [5.156].