Cosmetic powders ideally mixed in the amixon® mixer
Expectations are high when it comes to powdery cosmetic products such as eye shadow, powder or rouge: they should be easy to apply on the skin, last a long time and not crumble or create dust. In addition, they have to be treated particularly hygienically like high-purity pharmaceuticals.
The powder mixture is primarily composed of talcum powder, colour and effect pigments, and glitter powder. Further components such as powdery and liquid binding agents are added to make the powders compressible and extrudable. Adhesion promoters ensure that the powder remains permanently on the skin until the makeup is removed. Colour and effect pigments have a tendency to agglomerate due to their fineness. If they are not sufficiently well distributed in the powder matrix, they can leave coloured stripes when applied to the skin. To that extent the mixing process step must be done with a great deal of shear energy.
The challenge in the mixing process is to distribute the components in a particularly deagglomerating and homogenous manner in order to achieve a reproducible colour and a fine-powdered end product. Other components create opalescent and "holographic" effects and must be mixed in with particular care.
Such multi-step operations are ensured in the amixon mixer by the dead-zone-free flow. The patented SinConvex® mixing tool rotates in the centre of the mixing chamber. The helical blade gathers the mixing goods at the periphery of the mixing chamber and transports them upwards. Once they reach the top, they flow downwards in the centre of the container. The components are ideally mixed at a slow rotational speed, irrespective of different particle sizes, bulk densities and flow properties. Technically ideal mixing qualities are achieved after about 40 to 160 revolutions of the mixing device, which practically cannot be improved any further. HighShear blades are used in the amixon mixers in order to avoid agglomerates. These protrude laterally into the mixing vessel and work at speeds of up to 3000 rpm. They deagglomerate, break up lumps and activate the surfaces.
Ultra-fine distribution of the liquid binding agents
The cutting rotors also support the next step in the manufacture of cosmetics: the ultra-fine distribution of the liquid binding agents. The use of cutting rotors enables the particularly effective homogenisation of liquid additions. Highly viscous liquid additions can be distributed into the powder. They are injected underneath the filling level directly into the area of action of the cutting rotor using a feeding lance. The distribution of the fluid thus takes place directly through vortex, friction and centrifugal effects with increased energy input. The lance can optionally be equipped with a nozzle and can be tempered if desired.
Following a short post-mixing time, the manufacturing process in the mixer is complete. The complete discharge of the mixing chamber takes place without de-mixing - in practice, discharging rates of up to 99.98% or more have been achieved under ideal conditions. Finally, automatic wet cleaning can be carried out using the patented WaterDragon® system.
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