Patent ID: 6200722
Filing Date: 2001-03-13
Classification: G03G

Abstract:
A process for making an electrophotographic toner comprising:(a) uniformly mixing at least one particulate metal oxide selected from titanium dioxide, silicon dioxide, and mixtures thereof with toner particles to form a mixture having 5 to 15 weight percent metal oxide; and(b) mixing the product of step (a) with additional toner particles at a mixing intensity .gtoreq.500,000 (cm/minute) minute sufficient to embed the at least one metal oxide particles into the toner particles and decrease the concentration of the at least one metal oxide on the surface of the toner particles;wherein in the mixed product of (b) the metal oxide is 0.1 to 5.0 weight percent of the mixed product; and the toner particles have on their surfaces:when titanium dioxide is employed, a metal oxide concentration in a ratio of 1.0-3.0:1.0 with respect to titanium dioxide on the surface of the toner particles (determined in terms of atomic percent titanium based on total atomic elements present as measured by x-ray photoelectron spectroscopy):total bulk titanium dioxide in the mixed product; and when silicon dioxide is employed, a ratio of 10.0-25.0:1.0 with respect to silicon dioxide on the surface of the toner particles (determined in terms of atomic percent silicon based on total atomic elements present as measured by x-ray photoelectron spectroscopy):total bulk silicon dioxide in the mixed product.