AEROSIL® fumed silica for toner

Driving the technological advancement is a trend toward producing smaller particle sized toner.

Due to the greater difficulties in maintaining good flow and controlling charge, larger particle sized AEROSIL^® fumed silica grades such as RY 50, RX 50, NY 50 or NAX 50 are used in combination with smaller size AEROSIL^® grades such as R 972, R 812, R 805, RY 200, RY 200 S, RY 200 L, R 202, RX 200, RY 300 for negative-charged toners (particle size : 6~8 µm on average).

The two major benefits of using AEROSIL^® fumed silica in this application are:

1. Improvement of dry toner's flowability. Typical addition rates vary from 0.5-1.5 percent based on toner wt-percent.
2. Minimization of electrostatic charge variation at extreme conditions. The electrostatic charge of dry toner is stabilized at different ambient conditions such as 85 percent relative humidity, 40°C (Summer) and 20 percent relative humidity, 10°C (Winter). The typical addition rate for AEROSIL^® is 0.5~1.0 wt-percent.

Following these two guidelines, developing toners for clear and high-resolution copies is made easier in any environment using even the smallest particle size toners.

For positive charged toners, positive-charged AEROSIL^® fumed silica is used for free flow improvement and electrostatic charge stability in a variety of environments. AEROSIL^® fumed silica grades such as R 504, RA 200 HS and NA 50 H are widely used in positive charged toner formulations.

For full color toner, the combined use of hydrophobic AEROSIL^® fumed silicas such as NAX 50, R 972 or RX 50 and hydrophobic fumed Titanium oxides such as AEROXIDE^® TiO₂ NKT 90 or AEROXIDE^® TiO₂ T 805 or the combined use of hydrophobic AEROSIL^® fumed silicas such as RX 50, RY 50 and R 972 is recommended to stabilize the electrostatic charge of 4 color toners (black, cyan, yellow, magenta).