Hosokawa applies mixing technology to dry coating

Runcorn, UK - Hosokawa Micron Ltd has carried out trials to study the effectiveness of its Cyclomix high shear mixer as a dry coating device. The tests, on silica gel and starch particles, showed that the mixer offered a "controllable option" In many new application areas or where improvements to product functionality require the modification of surface properties, such as wetability, flowability, solubility, dispersibility, flavour or shape.

The study, carried out at the RAPSODEE Centre of the School of Mines in Albi, on the coating of starch particles with both hydrophilic and hydrophobic fumed silica  showed that the bulk density of the starch was increased significantly thus improving packing properties of the starch. The mixer, reportedly, did not damage the starch particles and the coating of fumed silica was seen to be individual particles set in the starch surface.

According to Hosokawa, dry powder surface coating can be used to achieve such surface modifications where the larger host particles (1-500µm) are mechanically coated with much smaller guest particles (0.1-500µm). This treatment, it said, creates a continuous or discrete coating and allows, under certain conditions, the design of multiple layering with different species of guest particles.

Hosokawa`s Cyclomix is a conical high impact mixer granulator which uses a specially designed high speed mixing paddle. When combined with the conical vessel shape, the paddle forces the material from the bottom to the top of the mixing vessel thus achieving efficient mixing. The design, said Hosokawa, is of particular value in new product development as the gentle action on materials so preserves the product characteristics.