In practice, a simple procedure has proven to yield satisfactory results: First the liquid component is put into the dispersion container. Then, under moderate agitation by the dissolver disc, pigments and fillers are added slowly. The dissolver disc speed can then be increased until the doughnut effect is detected at a higher rpm (circumference velocities of approximately 18 ‒ 25 m/s). After premixing, the walls of the dispersion container and the shaft should be cleaned removed adhering millbase.
High-speed is built-in !
Then the dispersion is carried out at high peripheral velocities that guarantee the formation of the doughnut effect. At this stage, the capability of the DISPERMAT® to transfer high mechanical power into the millbase should be exploited. One must not be afraid to use high rotational speeds. If e.g. an dissolver disc of 25 mm diameter is used, the DISPERMAT® must be run at a rotational speed of 15.000 rpm in order to obtain peripheral velocities of 20 m/s.
The final dispersion result is normally reached after 10 to 15 minutes. Use of the dissolver for a longer period of time is not likely to improve the result. Sample analysis shows that further deagglomeration does not take place. The particle size of demanding or difficult products can be reduced further using a DISPERMAT® bead mill or basket mill.