Лако-красочные материалы — производство

A particle size between 0.2 and 0.5 pm is preferred. High quality toners contain oxides with a narrow particle size distribution as demonstrated in Figures 5.6 and

5.7.

Fig. 5.6 Magnetite pigment for use in laser printer toners.

Fig. 5.7 Magnetite pigment for use in copier toners.

The coercivity and remanent magnetization [5.46] of a toner is, to a certain extent, dependent on the type of system used in the copying machine or printer. Many copier toners contain oxideswith a coercivity of7-9 kA m-1 while laser printer toners typically contain oxides with a lower coercivity in the region of 5 kA m-1. The coercivity of magnetite is governed by the production process, particle shape and particle size, and increases in the order spherical<cubical<octahedral particles [5.47]. Therefore, high quality laser printer toners contain spherical oxides (Figure 5.6) while most copier toners contain octahedral or cubical particles (Figure 5.7).

Producers of magnetic iron oxides for use in toners include Lanxess (Germany), Elementis, Magnox, Rockwood (USA), Kanto Denka K., Mitsui, Titan K., Toda K, (Japan) and Saehan (South Korea). World production in 2003 was ca. 30,000 t.

5.2