Even after storage and transport, powders must remain free-flowing without caking. SIPERNAT® special silica and AEROSIL® fumed silica are good anticaking agents and ensure good storage time stability and prevent caking. This is called the anticaking effect and is closely related to the free-flow effect.
Silica from Evonik are good antcaking agents
A powder’s pourability is crucial to how easily it can be dosed and used (free flow effect). This product property must be guaranteed at all times, even when the powder has been stored for a long time or transported to the customer, for example. Evonik offers a broad portfolio of SIPERNAT® specialty silica and AEROSIL® fumed silica for this purpose. They are highly effective even in small quantities. Even in substances that cake very easily, such as waxes and thermoplastic polymers, the storability is significantly enhanced.
Soft, malleable powder particles can become deformed during storage and cake. Hygroscopic powders absorb moisture and release it again, causing recrystallization.
SIPERNAT® specialty silica and AEROSIL® fumed silica products consist of fine silica agglomerates that envelop the particles of the powder to be treated (known as the host powder) and cause an anticaking effect. The powder particles are prevented from growing together.
To ensure that the effect lasts for as long as needed, slightly higher quantities of SIPERNAT® specialty silica and AEROSIL® fumed silica are needed for the anticaking effect than for a simple free flow effect.
Fine-particle SIPERNAT® specialty silica and AEROSIL® fumed silica products can be incorporated into the host powder simply by mixing. Suitable mixers include plowshare mixers, paddle mixers, and belt mixers.
For malleable, easily deformable powders or granulates, it is particularly important to ensure gentle mixing, so that the silica is not pressed into the surface of the powder particles.
You can find more detailed information on this topic in our Technical Information Sheets TI 1213, TI 1351 TI 1360 and TI 1365.