Toner aggregation and coalescence processes

A process for the preparation of toner compositions with a size of from about 1 to about 25 microns in average volume diameter comprising:

• (i) preparing a pigment dispersion in water, which dispersion is comprised of a pigment and an ionic surfactant;
• (ii) shearing the pigment dispersion with a latex mixture comprised of a counterionic surfactant with a charge polarity of opposite sign to that of said ionic surfactant, a nonionic surfactant, and resin, thereby causing a flocculation or heterocoagulation of the pigment and resin;
• (iii) stirring the sheared mixture at about 300 to about 1,000 rpm to form electrostatically bound stable toner size aggregates with narrow particle size distribution, which aggregates are of a particle size in the range of about 3 to about 10 microns in average volume diameter, and wherein said narrow particle size distribution or GSD is from about 1.16 to about 1.26;
• (iv) reducing the stirring speed to from about 200 to about 600 revolutions per minute and subsequently optionally adding additional ionic or nonionic surfactant in the range of from about 0.1 to 10 percent by weight, or water primarily to prevent further growth of the particles in the coalescence step (v);
• and
• (v) heating and coalescing from about 5.degree. C. to about 50.degree. C. above the resin Tg, which resin Tg is between about 45.degree. C. and about 90.degree. C., the statically bound aggregated particles to form said toner composition comprised of polymeric resin and pigment.

A process for the preparation of toner consisting essentially of:

• (i) preparing a pigment dispersion in water, which dispersion is comprised of a pigment, and an ionic surfactant in amounts of from about 0.5 percent to about 10 percent based on the amount of water;
• (ii) shearing the pigment dispersion with a latex mixture comprised of a counterionic surfactant with a charge polarity of opposite sign to that of said ionic surfactant, a nonionic surfactant, and resin, thereby causing a flocculation or heterocoagulation of the pigment and resin;
• (iii) further stirring of the resulting mixture to form electrostatically bound relatively stable toner size aggregates with a narrow particle size distribution;
• (iv) adding further surfactant to minimize further growth, or freeze the particle .size in the coalescence step (v), which size is from about 3 to about 10 microns in average volume diameter with a GSD of from about 1.16 to about 1.26;
• and
• (v) heating and coalescing, above the resin Tg the statically bound aggregated particles to form a toner composition comprised of resin and pigment.

A process for the preparation of toner compositions with a particle size of from about 3 to about 10 microns in average volume diameter consisting essentially of:

• (i) preparing a pigment dispersion in water, which dispersion is comprised of a pigment, an ionic surfactant in amounts of from about 0.5 to about 10 percent by weight of water, and an optional charge control agent;
• (ii) shearing the pigment dispersion with a latex mixture comprised of a counterionic surfactant with a charge polarity of opposite sign to that of said ionic surfactant, a nonionic surfactant, and resin particles, thereby causing a flocculation or heterocoagulation of pigment, resin particles, and optional charge control agent;
• (iii) stirring the mixture of (ii) at from about 300 to about 1,000 revolutions per minute to form electrostatically bound substantially stable toner size aggregates with a narrow particle size distribution, and wherein said stable toner size aggregates have a particle size in the range of from 3 to 10 microns in average volume diameter, and wherein said narrow particle size distribution is from about 1.16 to about 1.26;
• (iv) reducing the stirring speed in (iii) to from about 100 to about 600 revolutions per minute, and subsequently adding further ionic or nonionic surfactant in the range of from about 0.1 to about 10 percent by weight of water to prevent, or minimize further growth or enlargement of the toner size aggregates of (iii) in the coalescing step (v);
• and
• (v) heating and coalescing at from about 5.degree. to about 50.degree. C. above about the resin glass transition temperature, which resin glass transition temperature is from between about 45.degree. C. to about 90.degree. C. the electrostatically bound aggregated particles to form said toner composition comprised of resin particles, pigment particles and optional charge control agent particles.