×

Toner aggregation and coalescence processes

  • US 5,403,693 A
  • Filed: 06/25/1993
  • Issued: 04/04/1995
  • Est. Priority Date: 06/25/1993
  • Status: Expired due to Term
First Claim
Patent Images

1. A process for the preparation of toner compositions with a particle size of from about 1 to about 25 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;

    (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 coalescence step (v); and

    (v) heating and coalescing from about 5 to about 50°

    C. above about the resin glass transition temperature, Tg, which resin Tg is from between about 45°

    C. to about 90°

    C. the statically bound aggregated particles to form said toner composition comprised of resin particles, pigment and optional charge control agent.

View all claims
  • 4 Assignments
Timeline View
Assignment View
    ×
    ×