Fillers are particles added to material (plastics, composite material, concrete) to lower the consumption of more expensive binder material or to better some properties of the mixtured material. Worldwide, more than 53 million tons of fillers (with a total sum of approximately EUR16 billion) are used every year in different application areas, such as paper, plastics, rubber, paints, coatings, adhesives and sealants. As such, fillers, produced by more than 700 companies, rank among the world's major raw materials and are contained in a variety of goods for daily consumer needs.
Types of fillers
In the past, fillers were used predominantly to cheapen end products, in which case they were called extenders. Among the 21 most important fillers, calcium carbonate holds the largest market volume and is mainly used in the plastics sector. While the plastic industry mostly consumes ground calcium carbonate (GCC), the paper industry primarily uses precipitated calcium carbonate (PCC) that is derived from natural minerals. Wood flour and saw dust are used as filler in thermosetting plastic.
In some cases, fillers also enhance properties of the products, e.g. in composites. In such cases, a beneficial chemical interaction develops between the host material and the filler. As a result, a number of optimized types of fillers, nano-fillers or surface treated goods have been developed.