Sequenced addition of coagulant in toner aggregation process

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 70 to 99% by weight of a total amount of the resin latex dispersion to be added during the process 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) following completion of the adding of all of the counterionic coagulant, adding a remaining portion of the total amount of resin latex dispersion to be added during the process;
• (viii) adjusting the pH with a pH increasing agent to stabilize the aggregate particles;
• (ix) 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
• (x) optionally separating and drying the toner composition.