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Toner aggregation processes

  • US 5,366,841 A
  • Filed: 09/30/1993
  • Issued: 11/22/1994
  • Est. Priority Date: 09/30/1993
  • Status: Expired due to Term
First Claim
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1. A process for the preparation of toner compositions comprising:

  • (i) preparing a pigment dispersion in water, which dispersion is comprised of a pigment, an ionic surfactant and optionally a charge control agent;

    (ii) shearing the pigment dispersion with a latex blend comprised of resin particles, a counterionic surfactant with a charge polarity of opposite sign to that of said ionic surfactant and a nonionic surfactant thereby causing a flocculation or heterocoagulation of the formed particles of pigment, resin and optional charge control agent to form a uniform dispersion of solids in the water, and surfactant;

    (iii) heating the uniform disperion of solids in water and surfactant of (ii) at a critical temperature region about equal to or above the glass transition temperature (Tg) of the resin, while continuously stirring, to form electrostatically bounded toner size aggregates with a narrow particle size distribution and wherein said critical temperature is from about 0°

    C. to about 10°

    C. above the resin Tg, and wherein the resin Tg is from about 30°

    C. to about 65°

    C. and preferably in the range of from about 45°

    C. to about 65°

    C.;

    (iv) heating the electrostatically bounded toner size aggregates from about 10°

    C. to about 45°

    C. above the Tg of the resin particles to provide a toner composition comprised of polymeric resin, pigment and optionally a charge control agent; and

    (v) optionally separating and drying said toner.

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