Fillers are important additives for the improvement of various technical properties in paints, printing inks and plastics. Of special importance are synthetic amorphous silicas and silicates, which are produced in large quantities. Silicas are produced by precipitation of waterglass and acids, whereas silicates are produced by the addition of metal salts to the waterglass-acid-reaction. In both cases fine finely divided, amorphous, white powders are obtained with specific surface areas from 30 to 750 m²/g. Process variations such as precipitation, drying and milling enable “tailor made” products for a variety of applications. Precipitated silicas and silicates are offered in bags, in big bags and in silo trucks.
The worldwide production of synthetic amorphous silica and silicates via precipitation is about 1 Mio tons per year. More than half of this quantity is used as active reinforcing fillers in tires, shoe soles and technical rubber articles (rubber belt). The use as an active filler in silicon rubber is steadily increasing.
Further fields of application of these silicas is as a “free flowing powder” agent in easily adhering powders, as a support for liquid substances, coating for paper and antiblock agent for plastic foils. It is further used in batteries, toothpaste, beer production and many other applications.
Barium sulphate as Blanc Fix is a synthetic filler of excellent light-fastness and weather resistance; it is widely used in many paints and coatings. Blanc Fix is also suitable for high-quality plastic surfaces and for colour concentrate based on softening agents.
Synthetically produced, non stochiometric sodium silicates are mainly used for the coating of paper and as a pigment extender in water based paints for civil construction, as well as in rubber applications.
Synthetic, non stochiometric calcium silicate is mainly used as a filler in rubber applications.
Companies producing these groups of products within VdMi, can be found under our membership list.
Technical, ecological and legislative information can be found in the brochure “Colourants for food contact plastics”.