Toners

AEROSIL^® fumed silica is typically applied to improve flow and charge stability of toners. Performance enhancements such as improved resolution and print clarity of dry milled and chemically produced toner for laser printers or plain paper copiers have driven an increased usage.

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, RY 200 L, R 202 S, 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 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 NAX50, 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).