EIRICH Mixing and Dispersion Systems at the European Center for Dispersion Technologies

The European Center for Dispersion Technologies EZD is an interdisciplinary center, the only one of its kind in Germany, that was established by plastics center SKZ Kunststoffzentrum in close cooperation with industry and with support from the State of Bavaria to undertake development work in the production and characterization of dispersions (suspensions and emulsions). Following contact made at a trade fair, the EZD has supplemented its fleet of machines with an EIRICH EVACTHERM^® dispersion mixer.

SKZ has been providing independent services in plastics technology for both industry in 1961. Today, it is considered to be one of the biggest sector-specific institutes of its type. Over 350 staff work at its head office in Würzburg or in its branches – including in China, Iran and UAE – with that work also encompassing research and development projects as well as further training, certification and inspection. The R&D areas cover the entire spectrum, from additive production to dispersion to non-destructive testing. Activities relating to dispersion (formulation, analysis and dispersion techniques) are now exclusively bundled at Selb. The relevant services are offered for a wide range of sectors and applications, such as paint and coatings, nanocomposites, adhesives and matrices for fiber-reinforced composites. The laboratory facility needed for this is accordingly equipped for a wide range of tasks. Recently, this equipment has been supplemented with EIRICH/DE processing technology: a 1-lvacuum mixer with an Ex-protection finish, 4 kW drive power, with an accompanying condenser, vacuum pump retort and fully-automatic touch-panel controller. A variety of machine techniques is employed in the production of suspensions and emulsions. In most cases, it is a characteristic of mechanical dispersion processes that the dispersion tool is required to perform both the moving of the materials and the actual dispersion/deagglomeration. Moreover, generally machines are only equipped for a given range of dispersion viscosities; consequently, manufacturing processes often necessitate system interconnections for different processing stages. This is where the EIRICH mixing and dispersion system differs significantly from products by other manufacturers.

In the EIRICH dispersion mixer, a rotating pan handles moving the materials, and for that reason the tool – positioned off-center in the pan – can be designed optimally for the dispersion process. The separation between materials transport and the mixing or dispersion process also makes it possible to vary the tool speed (and thus the power input into the mix) between broad limits and to adjust it to the respective dispersion task. As a result, all viscosity ranges and consistencies (from dry to plastic to suspension) can be worked in this unique system; frequently, this allows for particularly economical single-unit processes.

For use at the EZD, it means that the dry pre-mix of different raw materials and also dry dispersion can be performed using the EIRICH mixer. By adding water or solvents the plastic phase is initiated, in which the mix is wetted, homogenized and dispersed with high power input. The desired solid content or the desired viscosity is then established by adding further liquid. Both low-viscosity and high-viscosity dispersions can thus be produced within a short time – often in less than 15 min. Alternatively, it is of course possible to manufacture in the conventional manner with a receiving fluid and adding the solids, as is customary with dissolvers. However, the best and most economical results in industrial use can be achieved by employing the dry mixing – kneading – dispersion mode.

Using EVACTHERM^® vacuum technology brings further advantages for the EZD. Dry mixing achieves significantly better loosening of agglomerates; eliminating the buffering air significantly increases the power input; and shearing forces can be introduced into the product with greater efficiency. Kneading and dispersion under vacuum ensures bubble-free suspensions, e.g. for downstream coating processes. Naturally, it is also possible to work under inert gas, or to heat and cool the product using ultraefficient evaporation cooling. EIRICH technology is used worldwide in many sectors, for mixing, granulating, coating, kneading and dispersion – with all this being possible in one and the same machine. For capacities of 1–3000 l just a single mixing or dispersion tool is needed. This results in very good scale-up capability for this processing system. EIRICH dispersion mixers are in use today e.g. in the ceramics industry, in the production of casting slurries and spray slurries or dispersions for the tape casting process. Further applications are the manufacture of coating pigments for the paper industry, carbon-water suspensions, foam concrete, microsilica processing, toners, colour pigment suspensions, sealing or road marking compounds and coating compounds for Li-ion batteries. This generates cost savings of up to 50 % compared with other processing systems. Process times are significantly shortened, with souring/maturing periods mostly no longer required. Battery compounds exhibit up to 20 % improved electrochemical properties, purely from improved dispersion, to mention just the most significant advantages. It also means that production machines can be equipped with automatic wet cleaning, allowing for simple product change.