Process for lowering charge/mass ratio of toner particles having controlled morphology and containing quaternary ammonium tetraphenylborate charge control agents

A process for lowering the charge/mass (Q/m) ratio of toner particles formed by limited coalescence, said process comprising:

• forming an organic phase comprising a polymeric material, a pigment, a quaternary ammonium tetraphenylborate salt, and a water-immiscible liquid, said polymeric material being selected from the group consisting of an acrylic resin, a methacrylic resin, a styrene-acrylic resin, a styrene-methacrylic resin, a polyamide, and a polyester;
• dispersing said organic phase in an aqueous phase containing a solid colloidal stabilizer;
• forming a suspension of small droplets of said organic phase in said aqueous phase by high shear agitation;
• removing said water-immiscible liquid from said small droplets, thereby forming a suspension of small solid particles in said aqueous phase, said particles having a non-spherical shape;
• and
• separating said solid particles from said aqueous phase and drying said particles,
• wherein said quaternary ammonium tetraphenylborate salt is included in said organic phase in an amount effective for lowering the charge/mass (Q/m) ratio of said toner particles, said quaternary ammonium tetraphenylborate salt being selected from the group consisting of salts represented by the general formulas (I), (II), (III), and (IV), and mixtures thereof:
• 28
• wherein R1 represents a substituted or unsubstituted alkyl or aryl group;
• R2 represents an alkylene or arylene group;
• R3, R4, and R5 independently represent a substituted or unsubstituted alkyl group, and R3 and R4 taken together may form a cyclic ring system;
• and R6 represents hydrogen or a substituted or unsubstituted alkyl group;
• 29
• wherein R1 represents a substituted or unsubstituted alkyl or aryl group;
• R2 represents an alkylene or arylene group;
• R3, R4 and R5 each independently represents a substituted or unsubstituted alkyl group;
• and R3 and R4 taken together may form a cyclic ring system;.
• 30
• wherein R1, R2, R3 and R4 each independently represents an alkyl or substituted alkyl group, and R1 and R2 taken together may form a cyclic ring system;
• 31
• wherein R1, R2 and R3 each independently represents an alkyl or substituted alkyl group and R1 and R2 taken together may form a cyclic ring structure;
• Z, if present, represents at least one monomer copolymerizable with a monomer comprising a tetraphenylborate salt substituent;
• m and n represent the weight percentages in a polymerization mixture of, respectively, said monomer comprising a tetraphenylborate salt substituent and Z, m and n together totaling 100.