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AssigneeXerox Corporation
InventorsAllan K. Chen, Tie Hwee Ng, Lu Jiang, Kimberly D. Nosella, Paul J. Gerroir, Michael Damato
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A method of forming an aqueous dispersion of particles of zinc stearate includes the steps of forming a mixture of at least one surfactant and water, heating the mixture to a temperature of from about 40° C. to less than a melting temperature of zinc stearate, adding a metal-containing stearate to the mixture under agitation, adding to the mixture a solution of a zinc salt in water, whereby upon inclusion of both the metal-containing stearate and the zinc salt in the mixture, the zinc salt reacts with the metal-containing stearate to form the particles of zinc stearate, continuing the heating and agitation following completion of the latter of the adding of the solution of zinc salt or the adding of the metal-containing stearate to continue the reaction, and cooling to obtain the aqueous dispersion of particles of zinc stearate. The method forms a stable aqueous dispersion of nanometer sized zinc stearate particles particularly useful in coating toner particles.
A method of forming an aqueous dispersion comprised of particles of zinc stearate, the method comprising
A method of forming toner particles coated with zinc stearate particles, the method comprising
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Organo-metallic compounds: metallic soaps of higher carboxylic acids
Electrography
Term end not estimated
1. Field of Invention
The invention relates to an in-situ method of forming an aqueous zinc stearate dispersion. The aqueous dispersion of zinc stearate finds particular utility as an external additive for toner, and more specifically as an external additive to a toner particle used as a cleaning additive in a developer composition.
2. Description of Related Art
This Example prepares a zinc stearate dispersion by a preferred process of the present invention. 24.3 g zinc acetate is dissolved in 252 g deionized water at room temperature. Separately, a diluted surfactant solution (8.62 g NEOGEN SC in 1,000 g deionized water) is then heated to 60° C. Into the heated surfactant solution, 77.7 g of the sodium stearate is added at once under high-shear, high-speed mixing at around 4,000 rpm. This is followed by adding the zinc acetate solution over approximately 10 minutes. Mixing at 60° C. is continued for 3 minutes at 8,000 rpm.
Then, the content is cooled down to less than 30° C. in about 5-10 minutes. Total process is about 1 hour.
The zinc stearate used is a zinc salt of commercial stearic acid with a melting point of about 140° C. The zinc stearate emulsification process is carried out at a temperature of 140° C. so that the zinc stearate particles become molten and hence breakable. A surfactant, NEOGEN SC, which contains about 65% of sodium dodecylbenzene sulfonate in water, is added to stabilize the zinc stearate particles.