Patent ID: 6120967
Filing Date: 2000-09-19
Classification: G03G

Abstract:
A process for the preparation of a toner composition comprising:(i) forming a resin latex dispersion of a resin in an aqueous ionic surfactant solution from a latex utilizing an ionic surfactant and optionally a nonionic surfactant;(ii) preparing a pigment dispersion in water of a pigment dispersed in water and a nonionic dispersant, and optionally an ionic surfactant of the same polarity as that employed in preparing the resin latex dispersion of step (i),(iii) blending the resin latex dispersion with the pigment dispersion, and optionally a wax dispersion, to form a resin-pigment blend;(iv) adding a portion of a counterionic coagulant in an aqueous solution to the resin-pigment blend, while continuously subjecting the mixture to high shear, to induce a homogeneous gel of the resin-pigment blend, wherein the amount of the counterionic coagulant added is 25 to 90% by weight of a total amount of counterionic coagulant to be added during the process;(v) heating the sheared gel at temperatures below a glass transition temperature (Tg) of the resin while continuously stirring to form aggregate particles;(vi) following a period of time to permit stabilization of aggregate particle size, adding a remaining portion of the total amount of counterionic coagulant to be added during the process in one or more sequenced stages;(vii) adjusting the pH with a pH increasing agent to stabilize the aggregate particles;(viii) heating the aggregate particles at temperatures above the Tg of the resin followed by reduction of the pH to form coalesced particles of a toner composition; and(ix) optionally separating and drying the toner composition.