Iron-free grinding of selected quartz sand with a high SiO2-content in ball or vibration mills produces silica. The controlled particle size distribution is realized using rotor driven air separators.
It is used as cheap filler in plaster and some plastics to add strength, or just to reduce the amount of (expensive) resin needed to fill a mold.
For polymer systems, silica fillers are mainly used for property enhancements. The major improvements imparted by silica include increases in stiffness, strength, temperature resistance, dimensional stability, surface hardness and scratch resistance. These properties are in ever-increasing demand, as the surface requirements for plastics are growing too stringent for unfilled polymers. FILLERS:
Low oil absorption, high mechanical strength, chemical inertness and ideal optical characteristics are strong assets for quartz:
- Floor paints are resistant to wear and tear as a result of the hardness of quartz fillers
- Transparent silica fillers enable durable wood protection and also allow the decorative structure of the wood to remain visible
- In various polymer applications (PU, Epoxy, PET, PP) micronized quartz provides exceptional benefits. The cycle time reduction in die-casting is a result of the exceptionally high thermal conductivity. The durable optic matting of the surface gives synthetic grass and textile fibers a more natural look.
- Silica is an excellent raw material for chemical products and is applicable in acid reactors through inertia, e.g. in the production of titan dioxide.
Some of the potential advantages that can be gained are weather and chemical resistance, reduced raw material costs, reduced flammability, water resistance, better thermal conductivity, enhanced electrical properties and improved whiteness.
The introduction of finer particle size silica fillers gives improvements in strength and stiffness, as well as enhancing surface smoothness and gloss. There is also the benefit of reduced wear on contact parts during processing. It should be considered that due to the higher surface area of these products, viscosity will increase and filler loading will not be as high. Potentially this can be addressed by the use of a surface modified product.