The first step: wetting stage

The gas phase white silica, is slowly added to the barrel, the disperser is low-speed mixing, the speed is about 100-300 rpm, dispersed for 5-10 minutes, after the barrel completely wrapped fumed silica, increase the speed rating , so you can reduce the fume fly problem of fumed silica.

The second step: high-speed decentralized phase

The speed of the disperser is adjusted to 1500-4500 rpm and the linear speed is 15 m / s -20 / s. According to the speed limit of the disperser itself and the viscosity of the resin itself, adjust and disperse properly for 30-60 minutes. Determine the silica dispersion completely: no particles or white spots, with higher transparency, no fog, no white. Fineness: Fineness meter can be measured.

Attention questions:

As fumed silica is a nano-scale product. The average primary particle size of 7-16 nm, and the presence of aggregated particle size between 1-2 microns, the Van der Waals force between molecules is relatively large, is the most difficult to disperse an aid, it is proposed to disperse the first white gas Carbon black, appropriate to add dispersant or wetting agent to help disperse, so good dispersion, continue to disperse other additives and fillers, it should be noted that the dispersion process, due to thickening effect of fumed silica, making the dispersion Machine rotation process, resulting in relatively large friction, making the temperature of the resin system or local temperature may appear, so pay attention to the cooling problem, especially the epoxy resin system, the local high temperature easily lead to open ring epoxy, Or carbonization and other issues. Dispersing capacity of high-speed dispersion equipment is relatively limited, fine if the fine, then over three-roll machine, grinding machine, sand mill and so on. The finest can be fumed silica powder dispersed to 0.5 microns or less.